Anyone have a P/N for the AC high pressure switch?
01-26-2004, 01:57 AM
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Anyone have a P/N for the AC high pressure safety switch?
Little by little I'm taking care of the nagging little issues on the '87 Coupe I just picked up.
Today I decided to fix the A/C. I evacuated it, leak checked it, then added some dye just in case and recharged it. When I went to test it, I found two problems-- the switch to signal the ECM to turn the fan on wasn't working, and without that fan on the high side pressure went to 440psi (!!!) in a heartbeat. Therein lies the other problem-- the 430psi high pressure cut off switch didn't cut power to the clutch.
The A/C worked great though when I manually turned the fan on.
Back to the high pressure switch, I went to the dealer today and had them look up the A/C system; their computer and books seem to be wrong, because they show the SAME switch p/n for both the low pressure/cycling switch and the high pressure safety switch. That clearly can't be right, as the cycling switch and high pressure switches are totally different in specifications.
Does anyone have a valid part number for the high pressure cut out switch? Or is it really the same switch as the low pressure / cycling switch? I don't want to blow up a hose or worse yet something more expensive in the event the fan switch fails again.
Thanks,
Troy
[Modified by Banana_Z52, 10:57 PM 1/25/2004]
Today I decided to fix the A/C. I evacuated it, leak checked it, then added some dye just in case and recharged it. When I went to test it, I found two problems-- the switch to signal the ECM to turn the fan on wasn't working, and without that fan on the high side pressure went to 440psi (!!!) in a heartbeat. Therein lies the other problem-- the 430psi high pressure cut off switch didn't cut power to the clutch.
The A/C worked great though when I manually turned the fan on.
Back to the high pressure switch, I went to the dealer today and had them look up the A/C system; their computer and books seem to be wrong, because they show the SAME switch p/n for both the low pressure/cycling switch and the high pressure safety switch. That clearly can't be right, as the cycling switch and high pressure switches are totally different in specifications.
Does anyone have a valid part number for the high pressure cut out switch? Or is it really the same switch as the low pressure / cycling switch? I don't want to blow up a hose or worse yet something more expensive in the event the fan switch fails again.
Thanks,
Troy
[Modified by Banana_Z52, 10:57 PM 1/25/2004]
01-26-2004, 12:06 PM
#2
Le Mans Master
Re: Anyone have a P/N for the AC high pressure safety switch? (Banana_Z52)
Switches are different. Low Pressure opens at 25 psi; high pressure at 430 or so, fan at 233 psi and recloses at 190. Delco, http://www.acdelco.com shows two switches, but both look like the low pressure cut off (Check the Electrical heading). Try these guys http://www.ackits.com or NAPA. Seems strange that both the fan and high pressure switches are shot -
01-26-2004, 01:28 PM
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Re: Anyone have a P/N for the AC high pressure safety switch? (Banana_Z52)
I don't know diddley squart about air conditioning, but here is some info from my parts book. My illustration shows two switches, side by side, in the rear of the evaporator inlet tube. These switches are at the firewall end of the tube, which is a hard line. Part number, 10007057, carries the nomenclature, "Switch, A.C. cmpr press cycling". I think that is your high pressure switch. Part number, 14078970, is called, "Switch, A.C. cmpr eng cool temp" The first no. is listed to fit 1984- 1990, the second, 1985-1990. I hope this helps. If my stated locations, don't match yours, let me know and I'll look again. I think these are it. Let's see what your dealer thinks of THAT. Good luck, and...
RACE ON!!!
RACE ON!!!
01-26-2004, 01:57 PM
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Re: Anyone have a P/N for the AC high pressure safety switch? (CFI-EFI)
CFI-EFI:
My dealer's computer shows I need 2 each 10007057; however, that is just the cycling switch to cycle the clutch on and off. It will not work for the high pressure switch-- The computer is clearly wrong; the cycling switch will NOT work for the high pressure switch as the pressures (as pointed out by SunCr) they operate at are VERY different.
The ECM fan switch did come up exactly as you found, part number 14078970, "Switch, A.C. cmpr eng cool temp"
I did order one of the cycling switches and one of the fan switches, so my system will in fact be operational; I just won't feel safe running it unless I have a functional high pressure switch.
Somehow I need to track down the correct part number for the high pressure switch. I'm going to run by and see a friend at my local NAPA today and see if he can crossreference the high pressure switch number for me. I checked with another dealer this morning and they showed the same thing-- 2 of the 10007057's.
Troy
My dealer's computer shows I need 2 each 10007057; however, that is just the cycling switch to cycle the clutch on and off. It will not work for the high pressure switch-- The computer is clearly wrong; the cycling switch will NOT work for the high pressure switch as the pressures (as pointed out by SunCr) they operate at are VERY different.
The ECM fan switch did come up exactly as you found, part number 14078970, "Switch, A.C. cmpr eng cool temp"
I did order one of the cycling switches and one of the fan switches, so my system will in fact be operational; I just won't feel safe running it unless I have a functional high pressure switch.
Somehow I need to track down the correct part number for the high pressure switch. I'm going to run by and see a friend at my local NAPA today and see if he can crossreference the high pressure switch number for me. I checked with another dealer this morning and they showed the same thing-- 2 of the 10007057's.
Troy
01-26-2004, 09:10 PM
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Re: Anyone have a P/N for the AC high pressure safety switch? (Banana_Z52)
Like I said, I don't know diddley about AC. It seemed to me that, "A.C. cmpr press cycling press" switch was a "high pressure switch". MY book only calls for one of part number, 10007059. Where does your high pressure switch, install. I ought to be able to find it that way.
I do find a separate switch on the evaporator, called, "Switch, press cutoff". In the illustration, the application is 1985-1989. In the text, the discription is, "Switch, press cycling cutoff". In the text it shows for 1985, only. I'm guessing the year, part, is incomplete, because the 10007057 fits 1984-1990. I think this is it, because they show a different "cutoff" for 1984 and none after 1985. That, AND the illustration info. THAT part number is 3041596. Again, if this isn't it, tell me where is is installed. Good luck, and...
RACE ON!!!
I do find a separate switch on the evaporator, called, "Switch, press cutoff". In the illustration, the application is 1985-1989. In the text, the discription is, "Switch, press cycling cutoff". In the text it shows for 1985, only. I'm guessing the year, part, is incomplete, because the 10007057 fits 1984-1990. I think this is it, because they show a different "cutoff" for 1984 and none after 1985. That, AND the illustration info. THAT part number is 3041596. Again, if this isn't it, tell me where is is installed. Good luck, and...
RACE ON!!!
01-26-2004, 09:44 PM
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Re: Anyone have a P/N for the AC high pressure safety switch? (CFI-EFI)
CFI-EFI: my car has a switch mounted on the low side line exiting at the top of the evaporator; this is the compressor cycling switch. I believe this is what your book is describing. The high pressure switch (as the shop manual calls it) is mounted on the high side line which runs down by the exhaust manifolds. It is just forward of the pressure switch to work the cooling fan.
As far as clearing up the switches:
The cycling switch serves to turn the compressor off when the low side pressure dips too low; this is to prevent icing of the evaporator. This occurs in normal usage; more frequently at lower ambient temps or lower A/C settings where not as much cooling capacity is needed. The switch allows the compressor to run until the low side dips down to a point indicative of freezing, and then it kicks the compressor off until the pressure has risen sufficiently, and then the compressor cycles back on. The high pressure switch is a safety item; it will cut power to the clutch in the event of dangerously high system pressures, typically a result of a blockage, fan or fan switch failure, etc, to prevent bursting of a seal/hose/o-ring/compressor/etc.
Interesting findings from my NAPA trip.
We searched the computer, and then looked through several NAPA Temp books and also 2000, 2001, 2002, and 2003 copies of AC Delco A/C catalog. Every book listed that the car has a cycling switch, fan switch, and a low pressure switch. None of the books nor the computer made any mention of a "high pressure" switch. This is clearly in disagreement with the "high pressure" switch nomenclature in the shop manual. The switch in question, just to clarify, is located on the line running down near the exhaust manifolds and is just forward of the fan switch.
The books listed Delco #15-2352 as the cycling switch, and 15-1122 as the low pressure switch. What is interesting is the NAPA interchange manual showed that the two part numbers are interchangeable-- so the dealer's computer is right on saying I needed quantity 2; that is if the other switch down by the fan switch is indeed a low pressure switch. Again, I don't know what to think here. The low pressure cutoff duties are clearly taken care of by the cycling switch up at the evaporator box; there is simply no need for a redundant switch down on the lower line.
It is possible the new cycling switches are trinary switches-- meaning a low pressure open at ~24psi, a close pressure of say ~45 psi, and another high pressure open of ~430 psi? If that were the case then the single switch could function properly in both locations and the system would then have double redundancy (a nice feature!) The new switches are physically different than the originals, so this may very well be the case.
I think what I will do is install the new cycling switch and run the system with the current bad fan switch. If the new cycling switch doesn't cut the clutch out at ~430psi then the system clearly needs a dedicated high pressure switch. If the new cycling switch does in fact also serve as a high pressure switch, I'll go ahead and pick one up to install in the current location of my current bad high pressure switch.
Troy
[Modified by Banana_Z52, 6:49 PM 1/26/2004]
As far as clearing up the switches:
The cycling switch serves to turn the compressor off when the low side pressure dips too low; this is to prevent icing of the evaporator. This occurs in normal usage; more frequently at lower ambient temps or lower A/C settings where not as much cooling capacity is needed. The switch allows the compressor to run until the low side dips down to a point indicative of freezing, and then it kicks the compressor off until the pressure has risen sufficiently, and then the compressor cycles back on. The high pressure switch is a safety item; it will cut power to the clutch in the event of dangerously high system pressures, typically a result of a blockage, fan or fan switch failure, etc, to prevent bursting of a seal/hose/o-ring/compressor/etc.
Interesting findings from my NAPA trip.
We searched the computer, and then looked through several NAPA Temp books and also 2000, 2001, 2002, and 2003 copies of AC Delco A/C catalog. Every book listed that the car has a cycling switch, fan switch, and a low pressure switch. None of the books nor the computer made any mention of a "high pressure" switch. This is clearly in disagreement with the "high pressure" switch nomenclature in the shop manual. The switch in question, just to clarify, is located on the line running down near the exhaust manifolds and is just forward of the fan switch.
The books listed Delco #15-2352 as the cycling switch, and 15-1122 as the low pressure switch. What is interesting is the NAPA interchange manual showed that the two part numbers are interchangeable-- so the dealer's computer is right on saying I needed quantity 2; that is if the other switch down by the fan switch is indeed a low pressure switch. Again, I don't know what to think here. The low pressure cutoff duties are clearly taken care of by the cycling switch up at the evaporator box; there is simply no need for a redundant switch down on the lower line.
It is possible the new cycling switches are trinary switches-- meaning a low pressure open at ~24psi, a close pressure of say ~45 psi, and another high pressure open of ~430 psi? If that were the case then the single switch could function properly in both locations and the system would then have double redundancy (a nice feature!) The new switches are physically different than the originals, so this may very well be the case.
I think what I will do is install the new cycling switch and run the system with the current bad fan switch. If the new cycling switch doesn't cut the clutch out at ~430psi then the system clearly needs a dedicated high pressure switch. If the new cycling switch does in fact also serve as a high pressure switch, I'll go ahead and pick one up to install in the current location of my current bad high pressure switch.
Troy
[Modified by Banana_Z52, 6:49 PM 1/26/2004]
01-26-2004, 10:58 PM
#7
Safety Car
Re: Anyone have a P/N for the AC high pressure safety switch? (Banana_Z52)
Well...I'll be a horses you know what!
WTH was I thinking?
Yes, mine does have three switches. Sorry for the misinformation. :banghead:
[Modified by BBA, 6:59 PM 1/27/2004]
WTH was I thinking?
Yes, mine does have three switches. Sorry for the misinformation. :banghead:
[Modified by BBA, 6:59 PM 1/27/2004]
01-26-2004, 11:02 PM
#8
Safety Car
Re: Anyone have a P/N for the AC high pressure safety switch? (Banana_Z52)
It is possible the new cycling switches are trinary switches-- meaning a low pressure open at ~24psi, a close pressure of say ~45 psi, and another high pressure open of ~430 psi?
The low pressure side and the High pressure side are seperated by the orifice tube and will not be at the same pressure until the AC is turned off and pressures equalize across the orifice. This effectively means the low pressure side will NEVER reach anywhere near 430 PSI.
01-27-2004, 12:37 AM
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Re: Anyone have a P/N for the AC high pressure safety switch? (BBA)
BBA-- VERY odd. My 87 clearly has 3 switches. 1 up on the top line coming out of the evaporator box (the cycling switch), and then 2 on the lower line down by the exhaust manifolds (fan switch and high pressure switch.) I can take a picture if you want, but believe me, it's there! Maybe this was a mid year change.
As far as the trinary switch, what I meant was that perhaps the current service part is indeed a trinary switch and can thus serve as a high pressure cut switch if installed on the high side line.
If GM really built these things without a high pressure switch, that is absolutely STUPID. I know that some R-4 compressors had their own high pressure cut switch installed in the back of their case (held in with a snap ring); my compressor clearly doesn't have one. I would find it hard to believe that GM sent my car out without a high pressure switch (it is really a safety item after all); since my compressor doesn't have the internal switch, that leaves my 3rd switch down near the exhaust manifold the most likely candidate.
Troy
[Modified by Banana_Z52, 10:33 PM 1/26/2004]
As far as the trinary switch, what I meant was that perhaps the current service part is indeed a trinary switch and can thus serve as a high pressure cut switch if installed on the high side line.
If GM really built these things without a high pressure switch, that is absolutely STUPID. I know that some R-4 compressors had their own high pressure cut switch installed in the back of their case (held in with a snap ring); my compressor clearly doesn't have one. I would find it hard to believe that GM sent my car out without a high pressure switch (it is really a safety item after all); since my compressor doesn't have the internal switch, that leaves my 3rd switch down near the exhaust manifold the most likely candidate.
Troy
[Modified by Banana_Z52, 10:33 PM 1/26/2004]
01-27-2004, 01:18 PM
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Re: Anyone have a P/N for the AC high pressure safety switch? (Banana_Z52)
I'll go through this one more time. First, I can't blame this an a mid-year thing. My parts book covers 1984-1989, and some 1990s. Other instances show "partial year" applications. Between my two posts, I have given you three switch part numbers. I cannot comment on anyone's interchanges or supercessions. *I* think the problem is in the nomenclature or discription in my book. Three switches.
No. 1) At the evaporator cover, on the outside of the firewall. It installs in a "T" type arrangment (integral with the evaporator) that takes the hose to the accumulator. The text discribes it as, "Switch, press cycling cutoff". Elsewhere, in a chart I see it simply called, "Switch, low press". Part number, 3041596.
No. 2) At the other (lower) evaporator connection is a hard line running to the bottom connection on the condensor. The orfice installs here, in the evaporator tube. The nut for this tube faces downward. The tube then has a "U" in it and it travels downward. After it makes a 90* turn to head forward, there are two, soldered in, fittings for switches. One of these switches is called, "Switch, A.C. cmpr eng cool temp". Part number, 14078970.
No. 3) Installs next to #2. The text discription is, "Switch, A.C. cmpr press cycling". The illustration discription of that same part number is, "Switch, Cmpr Hi Press Cutoff". Part number, 10007057.
Three switches. Three specific locations. Three different and distinct part numbers. Interchanges and substitutions are between you and NAPA or whoever. The only thing more I can do, is come and fix it for you. And remember... I don't know diddley about air conditionong.
RACE ON!!!
PS. My money is on no. 3.
[Modified by CFI-EFI, 11:27 AM 1/27/2004]
No. 1) At the evaporator cover, on the outside of the firewall. It installs in a "T" type arrangment (integral with the evaporator) that takes the hose to the accumulator. The text discribes it as, "Switch, press cycling cutoff". Elsewhere, in a chart I see it simply called, "Switch, low press". Part number, 3041596.
No. 2) At the other (lower) evaporator connection is a hard line running to the bottom connection on the condensor. The orfice installs here, in the evaporator tube. The nut for this tube faces downward. The tube then has a "U" in it and it travels downward. After it makes a 90* turn to head forward, there are two, soldered in, fittings for switches. One of these switches is called, "Switch, A.C. cmpr eng cool temp". Part number, 14078970.
No. 3) Installs next to #2. The text discription is, "Switch, A.C. cmpr press cycling". The illustration discription of that same part number is, "Switch, Cmpr Hi Press Cutoff". Part number, 10007057.
Three switches. Three specific locations. Three different and distinct part numbers. Interchanges and substitutions are between you and NAPA or whoever. The only thing more I can do, is come and fix it for you. And remember... I don't know diddley about air conditionong.
RACE ON!!!
PS. My money is on no. 3.
[Modified by CFI-EFI, 11:27 AM 1/27/2004]
01-27-2004, 07:00 PM
#11
Safety Car
Re: Anyone have a P/N for the AC high pressure safety switch? (Banana_Z52)
Sorry for any misleading I may have caused man...I corrected my stupid mistake. Yes, I have three switches in mine too.
01-27-2004, 09:50 PM
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Re: Anyone have a P/N for the AC high pressure safety switch? (CFI-EFI)
CFI-EFI-- thanks for the rehash on the part numbers, it was more clear than your first post.
I went to the dealer today to pick up my switches and had them check out #3041596 for me after reading your last post. 3041596 came up as a compressor cycling/low pressure switch for about 4 dozen applications, but for Vette it listed 85-86 only. However, Delco's website shows that the 3041596 crossreferences to a 15-1122, which several places show IS needed on my car. It appears the dealer's computer is wrong here, I'm going with what you and Delco say. I will order up one tomorrow morning.
Basically, the dealer's computer should have shown the car needs 1 each 10007057 and 1 each 3041596; that's where I had the problem and the source of all the confusion. I guess I'll return the other 10007057.
Thanks everyone for helping to clear this up. I've really had the guys at the parts counter stumped lately with this car. Between the messed up numbers and nomenclature for the A/C switches and the computer showing several different oxygen sensors (and incorrect quantities required, they kept trying to sell me 2!), I think they've had enough of me for a while :smash:
Troy
[Modified by Banana_Z52, 7:01 PM 1/27/2004]
I went to the dealer today to pick up my switches and had them check out #3041596 for me after reading your last post. 3041596 came up as a compressor cycling/low pressure switch for about 4 dozen applications, but for Vette it listed 85-86 only. However, Delco's website shows that the 3041596 crossreferences to a 15-1122, which several places show IS needed on my car. It appears the dealer's computer is wrong here, I'm going with what you and Delco say. I will order up one tomorrow morning.
Basically, the dealer's computer should have shown the car needs 1 each 10007057 and 1 each 3041596; that's where I had the problem and the source of all the confusion. I guess I'll return the other 10007057.
Thanks everyone for helping to clear this up. I've really had the guys at the parts counter stumped lately with this car. Between the messed up numbers and nomenclature for the A/C switches and the computer showing several different oxygen sensors (and incorrect quantities required, they kept trying to sell me 2!), I think they've had enough of me for a while :smash:
Troy
[Modified by Banana_Z52, 7:01 PM 1/27/2004]
