Poor guy....
A/C Break down.
Thread Starter
Intermediate
Joined: Jun 2009
Posts: 46
Likes: 1
From: Tampa FL
A/C Break down.
So I decided to investigate why my ac was not working this weekend. I have the FSM and followed the flow chart. First thing was that the compressor wasn't engaging, so I added some refrigerant to the recommended amount (per the can's suggestion), and tried again. This time my the compressor engaged and cycled.
I followed all the way through the flow chart until I got to Chart D when it asks if the line right before the expansion tube (where the orifice is located) is cooler than the evaporator outlet line. My outlet line was a bit cooler, and according to the chart this meant a plugged orifice. At $3, I just decided to replace it.
I recharged the system and started over. The first time the ac ran a little bit cooler (only slightly though). I did notice that the expansion tube started frosting up for the first time. I thought this was a good sign. But it still wasn't blowing cold. I worked my way back through the chart, and the next step after checking the orifice is to check for a clocked part of the high preassure line. It said look for a frost spot. The only frost spot was the expansion tube....
Where should I go from here? Everything else seems to be working correctly. Should the expansion frost up? The old orifice barely had any trash in it at all (none of it was metal thank God).
I followed all the way through the flow chart until I got to Chart D when it asks if the line right before the expansion tube (where the orifice is located) is cooler than the evaporator outlet line. My outlet line was a bit cooler, and according to the chart this meant a plugged orifice. At $3, I just decided to replace it.
I recharged the system and started over. The first time the ac ran a little bit cooler (only slightly though). I did notice that the expansion tube started frosting up for the first time. I thought this was a good sign. But it still wasn't blowing cold. I worked my way back through the chart, and the next step after checking the orifice is to check for a clocked part of the high preassure line. It said look for a frost spot. The only frost spot was the expansion tube....
Where should I go from here? Everything else seems to be working correctly. Should the expansion frost up? The old orifice barely had any trash in it at all (none of it was metal thank God).
Instructor
Joined: Jul 2007
Posts: 132
Likes: 0
From: Austin Texas
So I decided to investigate why my ac was not working this weekend. I have the FSM and followed the flow chart. First thing was that the compressor wasn't engaging, so I added some refrigerant to the recommended amount (per the can's suggestion), and tried again. This time my the compressor engaged and cycled.
I followed all the way through the flow chart until I got to Chart D when it asks if the line right before the expansion tube (where the orifice is located) is cooler than the evaporator outlet line. My outlet line was a bit cooler, and according to the chart this meant a plugged orifice. At $3, I just decided to replace it.
I recharged the system and started over. The first time the ac ran a little bit cooler (only slightly though). I did notice that the expansion tube started frosting up for the first time. I thought this was a good sign. But it still wasn't blowing cold. I worked my way back through the chart, and the next step after checking the orifice is to check for a clocked part of the high preassure line. It said look for a frost spot. The only frost spot was the expansion tube....
Where should I go from here? Everything else seems to be working correctly. Should the expansion frost up? The old orifice barely had any trash in it at all (none of it was metal thank God).
I followed all the way through the flow chart until I got to Chart D when it asks if the line right before the expansion tube (where the orifice is located) is cooler than the evaporator outlet line. My outlet line was a bit cooler, and according to the chart this meant a plugged orifice. At $3, I just decided to replace it.
I recharged the system and started over. The first time the ac ran a little bit cooler (only slightly though). I did notice that the expansion tube started frosting up for the first time. I thought this was a good sign. But it still wasn't blowing cold. I worked my way back through the chart, and the next step after checking the orifice is to check for a clocked part of the high preassure line. It said look for a frost spot. The only frost spot was the expansion tube....
Where should I go from here? Everything else seems to be working correctly. Should the expansion frost up? The old orifice barely had any trash in it at all (none of it was metal thank God).
Check post #7 of the following thread :
http://forums.corvetteforum.com/c4-t...erter-arm.html
Do you have an AC gage set to check your High/Low pressures?
I assume your car is a '96, did you charge system with 32oz of R134 ?
Thread Starter
Intermediate
Joined: Jun 2009
Posts: 46
Likes: 1
From: Tampa FL
I do not think I vacumee out the system. I am not sure though what exactly you mean? How would I go about vacumming out the system.
It is a 96 LT1. I did have a guage and the compressor cycled on and off and the correct psi. I also unplugged the blower moter to verify that the system still cycled correctly. I charged the system with R134a. I don't think I used 32 oz worth. Probably only about 18 oz. Any more than that and the preassure is in the 'danger' region of the gauge. I could not find in the fsm what the preassure should be when the engine is off, so I just went by the information on the can.
I will also check out the other post. Thank you!
It is a 96 LT1. I did have a guage and the compressor cycled on and off and the correct psi. I also unplugged the blower moter to verify that the system still cycled correctly. I charged the system with R134a. I don't think I used 32 oz worth. Probably only about 18 oz. Any more than that and the preassure is in the 'danger' region of the gauge. I could not find in the fsm what the preassure should be when the engine is off, so I just went by the information on the can.
I will also check out the other post. Thank you!
Le Mans Master
Joined: May 2006
Posts: 9,226
Likes: 9
From: Irvine Ca
Moisture inside the system is freezing up. There is a lot for you to learn if you are not sure what vacuuming out a system would do.
Instructor
Joined: Jul 2007
Posts: 132
Likes: 0
From: Austin Texas
I do not think I vacumee out the system. I am not sure though what exactly you mean? How would I go about vacumming out the system.
It is a 96 LT1. I did have a guage and the compressor cycled on and off and the correct psi. I also unplugged the blower moter to verify that the system still cycled correctly. I charged the system with R134a. I don't think I used 32 oz worth. Probably only about 18 oz. Any more than that and the preassure is in the 'danger' region of the gauge. I could not find in the fsm what the preassure should be when the engine is off, so I just went by the information on the can.
I will also check out the other post. Thank you!
It is a 96 LT1. I did have a guage and the compressor cycled on and off and the correct psi. I also unplugged the blower moter to verify that the system still cycled correctly. I charged the system with R134a. I don't think I used 32 oz worth. Probably only about 18 oz. Any more than that and the preassure is in the 'danger' region of the gauge. I could not find in the fsm what the preassure should be when the engine is off, so I just went by the information on the can.
I will also check out the other post. Thank you!
Anyway, with only 18oz, your compressor will probably short cycle alot due to insufficient charge, and not engage long enough to yield cold air inside the cabin.
If you live in hot climate with high humidity, take a look at this chart to better understand the pressures as related to ambient temps and humidity:
Instructor
Joined: Jul 2007
Posts: 132
Likes: 0
From: Austin Texas
Good point. You do need to draw a vacuum to boil off moisture in your system. When you replaced the oriface tube, you introduced the atmosphere to your system.Here is a "How To" that my dad did. He would probably try to help you out, but he was banned from CF fo 6 months.... My dad ( CF member MikeC4 ), he is such a tally whacker.....
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Instructor
Joined: Jul 2007
Posts: 132
Likes: 0
From: Austin Texas
Bwah hah hah. Yeah my dad said he is going to use his time off and take a class to become more Politically Correct, even though he believes that PC is no more than a sophisticated and dangerous form of censorship and oppression, imposed upon the citizenry with the ultimate goal of manipulating, brainwashing and destroying the masses......
Burning Brakes
Joined: Apr 2009
Posts: 877
Likes: 0
From: Broken Arrow Oklahoma
Joe, i think i agree with your dad.
As others have mention you have to pull a vacuum before anything else. If you don't own a pump you might be able to rent one. I did before i got my electronic pump.
As others have mention you have to pull a vacuum before anything else. If you don't own a pump you might be able to rent one. I did before i got my electronic pump.
Thread Starter
Intermediate
Joined: Jun 2009
Posts: 46
Likes: 1
From: Tampa FL
18oz is just over half of what your system requires. When you say "Danger" reading, are you talking about those crazy colored gauges they sell that only hook up to the Low side??? These are garbage.
Anyway, with only 18oz, your compressor will probably short cycle alot due to insufficient charge, and not engage long enough to yield cold air inside the cabin.
If you live in hot climate with high humidity, take a look at this chart to better understand the pressures as related to ambient temps and humidity:
Anyway, with only 18oz, your compressor will probably short cycle alot due to insufficient charge, and not engage long enough to yield cold air inside the cabin.
If you live in hot climate with high humidity, take a look at this chart to better understand the pressures as related to ambient temps and humidity:
Thanks.As far as the chart, I seen the chart in the FSM. I want to be absolutely clear though: My ambient temp is right around 90 with > %50 humidity, so I need to be looking at the 185 to 270 psi for my refigerant? That seems like a lot. I am using the color coded gauges/R134 charging cans from the part store. Your saying I should ignore the gauge and try to put approximately 32 oz in?
Also, according to the FSM, I don't think it is running short cycles; I believe I read that it should cycle about 8 times per minute, which mine does.
Drifting
Joined: Sep 2003
Posts: 1,363
Likes: 7
From: 1994 LT1 Coupe 6-speed with FX3 & 2000 LS1 Vert 6-Speed with F45 Hunterdon County, NJ
AndrewMessier,
At what RPM are you testing the pressure? Whereas yours is a 96 (and presume associated 96 FSM), our 94 FSM notes as follows:
with a external fan (simulating driving air), and engine run at 2k for 5 min, check inside temp and high/low pressure -- believe it's then that the max cycling of 8/min applies, at idle, given your temps, the compressor would normally not cycle.
Regarding your 'mechanics' comments, was he aware the system was completely opened (as his comment sounds more applicable to a small leak)?
Also, how did you vent the freon -- if you just openned a line, you may have also reduced the amount of oil in the system, which will need to be replaced too.
Not that I'm a certified a/c guy (member suncr is great, but I've 'been around the block' quite a few times and fixed a few of them), I have always heard that once an a/c system is opened (as you did to replace the orifice) or has a massive leak, once resealed/fixed, a vacume 'must' be pulled to evacuate the air/moisture within, otherwise frosting and possible compressor damage can result.
At what RPM are you testing the pressure? Whereas yours is a 96 (and presume associated 96 FSM), our 94 FSM notes as follows:
with a external fan (simulating driving air), and engine run at 2k for 5 min, check inside temp and high/low pressure -- believe it's then that the max cycling of 8/min applies, at idle, given your temps, the compressor would normally not cycle.
Regarding your 'mechanics' comments, was he aware the system was completely opened (as his comment sounds more applicable to a small leak)?
Also, how did you vent the freon -- if you just openned a line, you may have also reduced the amount of oil in the system, which will need to be replaced too.
Not that I'm a certified a/c guy (member suncr is great, but I've 'been around the block' quite a few times and fixed a few of them), I have always heard that once an a/c system is opened (as you did to replace the orifice) or has a massive leak, once resealed/fixed, a vacume 'must' be pulled to evacuate the air/moisture within, otherwise frosting and possible compressor damage can result.
Thread Starter
Intermediate
Joined: Jun 2009
Posts: 46
Likes: 1
From: Tampa FL
He was aware.
I added about 10 oz more freon, and it finally began to cool. However, by today it evidently all leaked out because I was back to no a/c with the compressor short cycling. I think I found where the freon might be leaking out. At this point I am going to take it to an a/c specialist to repair the leak and properly service the system. I think I would rather pay a little now then risk replacing a $500+ compressor.
I appreciate your response. Suncr does sound like the ac master. It was after reading pages of his replies that I decided to let someone else properly go over the system.
I added about 10 oz more freon, and it finally began to cool. However, by today it evidently all leaked out because I was back to no a/c with the compressor short cycling. I think I found where the freon might be leaking out. At this point I am going to take it to an a/c specialist to repair the leak and properly service the system. I think I would rather pay a little now then risk replacing a $500+ compressor.
I appreciate your response. Suncr does sound like the ac master. It was after reading pages of his replies that I decided to let someone else properly go over the system.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
At this point I am going to take it to an a/c specialist to repair the leak and properly service the system. I think I would rather pay a little now then risk replacing a $500+ compressor.
I appreciate your response. Suncr does sound like the ac master. It was after reading pages of his replies that I decided to let someone else properly go over the system.
I appreciate your response. Suncr does sound like the ac master. It was after reading pages of his replies that I decided to let someone else properly go over the system.
Most people have at least seen it done and asked questions as they may have watched a pro AC shop service their own car in their early years perhaps. Picking up a book and doing AC work is not the common way and real bold.
It would definitely assist you in getting some practical experience and learning the do’s and don’ts. I think it’s a wise move to go and get it professionally serviced. Now is your opportunity to watch closely and ask questions. The big difference is the pros gave the recovery equipment that does multiple things. We don’t have that kind of equipment but the process is basically the same. Having a good set of gauges, vacuum pump and some knowledge can get you a long way.
Best of luck
Le Mans Master
Joined: Mar 2004
Posts: 8,700
Likes: 298
From: Ft. Lauderdale Fl
So I decided to investigate why my ac was not working this weekend. I have the FSM and followed the flow chart. First thing was that the compressor wasn't engaging, so I added some refrigerant to the recommended amount (per the can's suggestion), and tried again. This time my the compressor engaged and cycled.
I followed all the way through the flow chart until I got to Chart D when it asks if the line right before the expansion tube (where the orifice is located) is cooler than the evaporator outlet line. My outlet line was a bit cooler, and according to the chart this meant a plugged orifice. At $3, I just decided to replace it.
I recharged the system and started over. The first time the ac ran a little bit cooler (only slightly though). I did notice that the expansion tube started frosting up for the first time. I thought this was a good sign. But it still wasn't blowing cold. I worked my way back through the chart, and the next step after checking the orifice is to check for a clocked part of the high preassure line. It said look for a frost spot. The only frost spot was the expansion tube....
Where should I go from here? Everything else seems to be working correctly. Should the expansion frost up? The old orifice barely had any trash in it at all (none of it was metal thank God).
I followed all the way through the flow chart until I got to Chart D when it asks if the line right before the expansion tube (where the orifice is located) is cooler than the evaporator outlet line. My outlet line was a bit cooler, and according to the chart this meant a plugged orifice. At $3, I just decided to replace it.
I recharged the system and started over. The first time the ac ran a little bit cooler (only slightly though). I did notice that the expansion tube started frosting up for the first time. I thought this was a good sign. But it still wasn't blowing cold. I worked my way back through the chart, and the next step after checking the orifice is to check for a clocked part of the high preassure line. It said look for a frost spot. The only frost spot was the expansion tube....
Where should I go from here? Everything else seems to be working correctly. Should the expansion frost up? The old orifice barely had any trash in it at all (none of it was metal thank God).