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I was going to add some Freon to my 93 and I see this.
What the hell. Is that evaporator meant for a an Impala or something???
If I move the expansion tank, the AC fitting flexes.
That looks like a 134a fitting, I am not sure when GM changed over the C4, but if your car was originally charged with R12 then it was probably converted at some point.
That looks like a 134a fitting, I am not sure when GM changed over the C4, but if your car was originally charged with R12 then it was probably converted at some point.
The web says 93 chevys are 134a.
How hard is it to dig into the evaporator box?
Does anyone have any suggestions?
I know I can unmount the exp tank & put in Freon, but I suspect the fitting leaks due to all the vibrational stress it sees. This can't be right.
Don't trust the web, there should be a sticker under the hood with the type of refrigerant and amount of the charge. If your car was originally 134a than a PO could have installed an aftermarket evaporator.
That looks like a 134a fitting, I am not sure when GM changed over the C4, but if your car was originally charged with R12 then it was probably converted at some point.
correct - that's a r134a adapter fitting. i'm no expert, and I could be wrong, but i'm thinking that's where the low pressure cycling switch should be mounted. not 100% sure, and not an LT1 AC expert, but the low pressure service port should be on the accumulator/dryer, like most other C4's. here's a parts breakdown - the book actually calls it a thermo expansion valve -
look around for an electrical connector plug laying around in the vicinity of that r134a adapter.
here's a pic of my 85 - your 93 should look similar -
and, to answer some of the OP's original questions, the 93 corvette originally should have been R12, and from the looks of it, it looks like the correct evaporator core.
If I move the expansion tank, the AC fitting flexes.
Originally Posted by Joe C
I believe the question is about the flexing of the refrigerant line, not the operation of the a/c. The a/c has apparently been working okay.(?)
Looking at these two photos, the difference is the missing insulation between the a/c line and the housing. That would allow the a/c line to wiggle! I had the same problem on my '84! A chunk of foam weatherstrip stuffed in this area solved my problem. This missing chunk of foam also resulted in a cold air discharge (leak) from the a/c housing in my car. Cliff Harris noticed this missing insulation in my car during a recent get-together! Thanks, Cliff! ( I hope you're doing okay, Cliff!)
Thanks Joe.
I checked again and it looks like 93 was the last year for R12 Freon.
Looks like I have a really bubbauped system. Put in an early evaporator and then added on 134a Freon and maybe patched in a wire to make up for a lack of the pressure switch.
I will check the can area at the front of the engine for the stock fill port.
Thanks Joe.
I checked again and it looks like 93 was the last year for R12 Freon.
Looks like I have a really bubbauped system. Put in an early evaporator and then added on 134a Freon and maybe patched in a wire to make up for a lack of the pressure switch.
I will check the can area at the front of the engine for the stock fill port.
More on this tomorrow.
your low pressure service port should be located at the accumulator/dryer as shown -
Originally Posted by Hot Rod Roy
I believe the question is about the flexing of the refrigerant line, not the operation of the a/c. The a/c has apparently been working okay.(?)
i'm not reading that into the OP's original question. whether the A/C is working or not, that 93 corvette is not configured correctly. I would check if the electrical connector that should be plugged into the LP cycling switch - is there a jumper shorting the two electrical contacts. if not, the radiator cooling fan should be running constantly. I would also like to see a pic of the OP's accumulator/dryer.
added on 134a Freon and maybe patched in a wire to make up for a lack of the pressure switch. I will check the area at the front of the engine for the stock fill port.
I doubt you have a Bubba'ed system. I really doubt someone smart enough to do a 134a refrigerant upgrade would eliminate the low pressure switch! The system wouldn't work right without the switch. There's some reason the 134a fill port is in that unusual location. I'm sure you'll find the l/p switch.
I doubt you have a Bubba'ed system. I really doubt someone smart enough to do a 134a refrigerant upgrade would eliminate the low pressure switch! The system wouldn't work right without the switch. There's some reason the 134a fill port is in that unusual location. I'm sure you'll find the l/p switch.
I will have more photos later today or tomorrow.
But I will say: only a bubba would install an AC fitting that is touching another component in the engine bay.
I just popped outside and took a look at my 93 I have a pressure switch in that Same area but it Points toward the valve cover.
Looking at some of the photos that have been attached of the Earlier year cars makes me wonder if he has one made for something like an 86
I believe that '90 - '93 would be configured like your snapshot. My LT5 is pointed down but "away" from the engine. Call yours 120° and my LT5 maybe 210° from straight up. The one the OP has in his snapshot does appear to be an earlier car maybe through '89.
I'd think that before the OP goes about insinuating it was done by Bubba or his cousin he might think about his "inspection" before purchase. I'd thought this might have been questioned before money changed hands. I can't imagine most overlooking it. It could be a very well thought out approach to a repair. PO might know - maybe a very experienced C4 guy knew "just what to do"!!
I doubt you have a Bubba'ed system. I really doubt someone smart enough to do a 134a refrigerant upgrade would eliminate the low pressure switch! The system wouldn't work right without the switch. There's some reason the 134a fill port is in that unusual location. I'm sure you'll find the l/p switch.
"smart enough" - oh really? . the system would work without an actual switch if the pins on electrical connector were shorted. that would apply a power signal to the heater/AC controller which in turn controls the A/C clutch relay and A/C clutch. whether the system works correctly or not is another thing, but it sounds to me like maybe someone was trying to bypass a pressure switch and force the system into full time "on" mode. the only place I could see someone relocating the low pressure switch would be at the accumulator/dryer, but I don't know how the inside of the accum/dryer is configured. so i'm not sure if that's a viable option. then you'd have to ask "why?" i'm starting to wonder if the OP has the correct evaporator core in the 93.
we really need to see the big and complete picture, especially that electrical connector, and if there's an actual LP cycle switch in the system, but with first impressions, something's not right. whether it been "bubba'd" or not is another thing.
In a '93, wouldn't that give you an error code? With the pressure in the system bouncing against the high pressure safety cut-off switch?
maybe - ??? - I don't know. I would think if there was sufficient Freon in the system it would not throw a code. if high and low pressures were within proper operating ranges, the ECM would see everything as normal.
too many unanswered questions. the OP needs to supply more info...
maybe - ??? - I don't know. I would think if there was sufficient Freon in the system it would not throw a code. if high and low pressures were within proper operating ranges, the ECM would see everything as normal.
too many unanswered questions. the OP needs to supply more info...
The high pressure switch is just a safety, if the system is operating properly it should never come into play.
There are two basic configurations for the evaporator. Early with the fitting pointing outboard and later with it pointing inboard. It gets a little sketchy as some catalogs show one and some show the other for the later type. 4 Seasons shows the wrong part. If you look at Rock Auto they have both ways shown.
I have a new evaporator here with the fitting pointing outboard from 4 Seasons. I've had it sitting here forever and don't have the original box anymore but I think I got this for a later C4 and obviously didn't use it.
That 90 degree fitting is very a very typical part. My guess is that someone got this all together ran into this problem and moved the transducer to the accumulator to make it all work. I'm just not too keen on the elbow up against the expansion tank but I guess it worked this long. I guess we'll see...
No, these later vettes use a variable output transducer not the simple switch as on the earlier ones.
are you sure about that? I could be wrong here, but looking at my 96 FSM, for both AC systems (RPO C60 manual and C68 electronic), it shows a simple on/off pressure switch for the LP cycling. C60 - open at 24.5 psi, close at 47 psi. for C68, open at 23 psi, close at 46 psi. nowhere does it show a transducer. however, IIRC, the LP switch does have a manual adjustment screw to tweak or fine tune the on/off pressures. an adjustment is necessary since the operating pressures differ from R12 vs. R134a. the function of the screw adjustment is to slide the on/off pressure window up or down the pressure scale. if it was a transducer, as you say, it would have to convert the pressures into a variable electrical signal feeding some other controller. the service schematics do not show it that way, but rather, just a simple 2-wire on/off pressure switch.
when I converted my 85 from R12, I purchased a (non-adjustable) LP cycling switch that was designed or pre-set for R134a operating pressures.
Originally Posted by Tod Stiles
There are two basic configurations for the evaporator. Early with the fitting pointing outboard and later with it pointing inboard. It gets a little sketchy as some catalogs show one and some show the other for the later type. 4 Seasons shows the wrong part. If you look at Rock Auto they have both ways shown.
I have a new evaporator here with the fitting pointing outboard from 4 Seasons. I've had it sitting here forever and don't have the original box anymore but I think I got this for a later C4 and obviously didn't use it.
That 90 degree fitting is very a very typical part. My guess is that someone got this all together ran into this problem and moved the transducer to the accumulator to make it all work. I'm just not too keen on the elbow up against the expansion tank but I guess it worked this long. I guess we'll see...
if that is the case, the OP may try this - i'm thinking the factory flare fitting on the evaporator may be a 1/4" or AN-4. a standard, AN-4, 90° elbow MAY be smaller than the R134a, 90° adapter. this may give enough clearance that the fitting would not interfere with the expansion tank. after the AN-4 elbow, a straight R134a adapter could be used. the same may apply if the fitting is a 3/16" (AN-3) -
edit: we may be talking apples and oranges here. i'm assuming we're talking about the low pressure cycling switch, and you my be referencing the (high pressure) A/C refrigerant pressure sensor. that appears to be some sort of a transducer feeding a (variable) electrical signal back to the powertrain control module. if that's the case, sorry for the confusion.
06-27-2017, 02:35 PM
Is this a knuckleheaded fix of an AC evaporator?
. the system would work without an actual switch if the pins on electrical connector were shorted. that would apply a power signal to the heater/AC controller which in turn controls the A/C clutch relay and A/C clutch. whether the system works correctly or not is another thing, but it sounds to me like maybe someone was trying to bypass a pressure switch and force the system into full time "on" mode. the only place I could see someone relocating the low pressure switch would be at the accumulator/dryer, but I don't know how the inside of the accum/dryer is configured. so i'm not sure if that's a viable option. then you'd have to ask "why?" i'm starting to wonder if the OP has the correct evaporator core in the 93. 
