Hey Guys, A/C Help
07-24-2009, 10:16 PM
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Hey Guys, A/C Help
Well when I bought my 88 off the old man in 2005 the A/C was one of the things that didn't work... Well now that I am moving to AZ, I wanted to see what was up. He said the freeon leaked out and he didn't drive it so he didn't ever get it fixed.
I take it in today and the dude went ahead and converted it over to R-134, fixed the leak, and charged it up for me. Well it was sitting there in the shop, blowing cold, but then as soon as I started driving away it was hot air comin' out... So I get home and mess around with the temp control and whatnot and make a call over to Corvette Mike's and they tell me to bring it in and it could take an hour or two just to figure it out, then the cost to fix it... Well that sucks. Now what exactly is happening is that when the car is sitting, at idle, it blows reasonably cold, yay, well AS SOON AS I PRESS ON THE ACCELERATOR PEDAL IT STARTS BLOWING HOT... What the hell....? The I turn the system off and turn it back on and mess around with it and it starts blowing cooler again. It seems to blow cold as hell out of the defrost vent... But I can't figure out why as soon as I start driving or press the pedal it starts blowing hot air? Now before I ever charged the air, I would just be driving down the freeway with the top off or windows open, and it would start blowing hot air on my feet, like, REALLY HOT AIR to the point I would turn the system on low and put it out of the defrost vent just so I didn't have to feel it on my feet. Another thing too, during the winter when it was cold, I used to turn the system on at 60 degrees just to allow the cool air to vent in the car, but the same thing would happen where it would just intermittently change over to hot air even though the A/C compressor wasn't running and I was just running the outside air through the car... I don't get any of this ****, I'd like to not have to pay a shop a lot of money just to "find out" what the problem is, any direction would be greatly appreciated. Thanks.
I take it in today and the dude went ahead and converted it over to R-134, fixed the leak, and charged it up for me. Well it was sitting there in the shop, blowing cold, but then as soon as I started driving away it was hot air comin' out... So I get home and mess around with the temp control and whatnot and make a call over to Corvette Mike's and they tell me to bring it in and it could take an hour or two just to figure it out, then the cost to fix it... Well that sucks. Now what exactly is happening is that when the car is sitting, at idle, it blows reasonably cold, yay, well AS SOON AS I PRESS ON THE ACCELERATOR PEDAL IT STARTS BLOWING HOT... What the hell....? The I turn the system off and turn it back on and mess around with it and it starts blowing cooler again. It seems to blow cold as hell out of the defrost vent... But I can't figure out why as soon as I start driving or press the pedal it starts blowing hot air? Now before I ever charged the air, I would just be driving down the freeway with the top off or windows open, and it would start blowing hot air on my feet, like, REALLY HOT AIR to the point I would turn the system on low and put it out of the defrost vent just so I didn't have to feel it on my feet. Another thing too, during the winter when it was cold, I used to turn the system on at 60 degrees just to allow the cool air to vent in the car, but the same thing would happen where it would just intermittently change over to hot air even though the A/C compressor wasn't running and I was just running the outside air through the car... I don't get any of this ****, I'd like to not have to pay a shop a lot of money just to "find out" what the problem is, any direction would be greatly appreciated. Thanks.
Last edited by D0St0V3L; 07-24-2009 at 11:24 PM.
07-25-2009, 12:21 AM
#2
Drifting
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Do you have an FSM for your car? If not, it will help alot to have one.
Can you duplicate the AC heating up when driving by just sitting in the driveway and increasing the RPMs?
If so, then suggest raising the hood and seeing if the AC compressor clutch is cycling off when the RPMs are raised.
If so, this may be happening either:
1. because is should, and the problem is the mixing door which is not positioning correctly
2. freon is low and when the rpm's of the compressor are raised, the natural effect is to lower the low-pressure side's pressure, which will cause the low-pressure switch to cycle the compressor off.
3. the high-pressure's high/low pressure switch and low-pressure's compressor-cycling pressure switches are still set for R12. Some are adjustable others must be replaced when converted to R-134a.
Can you duplicate the AC heating up when driving by just sitting in the driveway and increasing the RPMs?
If so, then suggest raising the hood and seeing if the AC compressor clutch is cycling off when the RPMs are raised.
If so, this may be happening either:
1. because is should, and the problem is the mixing door which is not positioning correctly
2. freon is low and when the rpm's of the compressor are raised, the natural effect is to lower the low-pressure side's pressure, which will cause the low-pressure switch to cycle the compressor off.
3. the high-pressure's high/low pressure switch and low-pressure's compressor-cycling pressure switches are still set for R12. Some are adjustable others must be replaced when converted to R-134a.
07-25-2009, 06:32 AM
#3
Le Mans Master
I have an 86, and I understand your pain
What is happening is the vacuum is low because of a vacuum leak somewhere. When you sit and idle, the vacuum is the highest, and the heater valve is being held closed with the vacuum. as soon as you give it gas, the heater valve opens, heating up the heater core, and the air door shifts a little, and the hot hot air overcomes the AC air, and it takes a while for the heat to dissipate, and the AC to get the air path cold again. Change speeds, or take off from a start, and it happens all over again.
You can use a wire tie, and position the heater valve in the off position till summer is over, and when it's cool enough to be working on a hot car, you can trace your vacuum leak. Just be aware that the vacuum leak tht you have will affect everything in the car.
fuel mixture, mileage indications, environmental, etc.
What you can do, till it's cooler, is remove the top of the dash, find the vacuum motor next to the windshield where the defroster lever is, make a little aluminum bracket to keep the defroster off, and then after summer is over, get the vacuum back.
Just be aware, that it and the heater valve are spring loaded open. In the dead of winter in Michigan, you can freeze to death if the heater doesn't work, so they spring load those things to work. In the summer in Michigan, you can drink lots of water and still survive.
It doesn't matter that you live in a place that doesn't snow, it's what's good for the masses.
I actually drilled a small hole in the heater valve bracketry, and made a little link, like choke linkage on a carbed engine, and I can remove the link when it's winter out, and the heater works good.
I also made the little bracket for the defroster since it hardly ever rains here, and the humidity level is usually around 14%. When it cools off, I am going to try to change alll the plastic vacuum tubing in the car.
I was where you are; and then after tracing some things, got to the point where the vacuum line goes through the firewall in the computer harness, and then it's just too hot here to fight it now.
I changed out the temp controller and the programmer, and no change. So I know it's not that.
The vacuum on the heater vacuum hose goes away when I drove, because I taped a vacuum gauge on the windshield and went for a drive. I could watch the vacuum, and feel the heat kick in.
Note:
do not tape anything to your windshield in the summer. getting the melted glue off the glass can prove to be challenging.
What is happening is the vacuum is low because of a vacuum leak somewhere. When you sit and idle, the vacuum is the highest, and the heater valve is being held closed with the vacuum. as soon as you give it gas, the heater valve opens, heating up the heater core, and the air door shifts a little, and the hot hot air overcomes the AC air, and it takes a while for the heat to dissipate, and the AC to get the air path cold again. Change speeds, or take off from a start, and it happens all over again.
You can use a wire tie, and position the heater valve in the off position till summer is over, and when it's cool enough to be working on a hot car, you can trace your vacuum leak. Just be aware that the vacuum leak tht you have will affect everything in the car.
fuel mixture, mileage indications, environmental, etc.
What you can do, till it's cooler, is remove the top of the dash, find the vacuum motor next to the windshield where the defroster lever is, make a little aluminum bracket to keep the defroster off, and then after summer is over, get the vacuum back.
Just be aware, that it and the heater valve are spring loaded open. In the dead of winter in Michigan, you can freeze to death if the heater doesn't work, so they spring load those things to work. In the summer in Michigan, you can drink lots of water and still survive.
It doesn't matter that you live in a place that doesn't snow, it's what's good for the masses.
I actually drilled a small hole in the heater valve bracketry, and made a little link, like choke linkage on a carbed engine, and I can remove the link when it's winter out, and the heater works good.
I also made the little bracket for the defroster since it hardly ever rains here, and the humidity level is usually around 14%. When it cools off, I am going to try to change alll the plastic vacuum tubing in the car.
I was where you are; and then after tracing some things, got to the point where the vacuum line goes through the firewall in the computer harness, and then it's just too hot here to fight it now.
I changed out the temp controller and the programmer, and no change. So I know it's not that.
The vacuum on the heater vacuum hose goes away when I drove, because I taped a vacuum gauge on the windshield and went for a drive. I could watch the vacuum, and feel the heat kick in.
Note:
do not tape anything to your windshield in the summer. getting the melted glue off the glass can prove to be challenging.
Last edited by coupeguy2001; 07-25-2009 at 11:57 AM.
07-25-2009, 12:51 PM
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Hey guys I really appreciate the help!
coupeguy2001, since I really have no mechanical skill and I'm actually kinda nervous to touch the car and take things apart since I may not be able to put it back together, could I give ya some money to help me with that little mod once I move out to AZ?
Whatever you think it may be worth to ya if you're willing!!!!
coupeguy2001, since I really have no mechanical skill and I'm actually kinda nervous to touch the car and take things apart since I may not be able to put it back together, could I give ya some money to help me with that little mod once I move out to AZ?
Whatever you think it may be worth to ya if you're willing!!!!
07-25-2009, 06:30 PM
#5
Le Mans Master
You are moving here? oh Lordy..........
The heater valve thing is easy. you can do it with a patch over one eye singing "dead man's chest".
Sure I'll help, but for now,
Just open the hood, go to the right side, you will see 2 tubes, one will have a small tube going into the engine about a foot from the car going forward. Those are the heater valve tubes.
You will see a interconnect piece between those tubes. that is the heater valve. You see the little piece that looks like a pendulum with a slot in it.
That is the link you need to pull and lock with a piece of wire. that will turn off the heater till you can get it fixed.
The dash is held in with two screws, one on either side of the defroster duct, and under the dash pad, there are 4 screws holding the bottom.
take out all the screws, and pull the dash pad straight back towards you and up a little.
It will come off with a little resistance.
Once you get it off, you can look down through the windshield, and on the left side of the defrost duct is the link that pulls the duct shut.
Get inside, sit in the driver's seat, you can pull the duct shut.
you can make a little holder from a coat hanger to hold the spring loaded valve shut. then most of the air will go through the front of the dash, and down on your legs. This will be enough air conditioning to get u through the summer.
The heater valve thing is easy. you can do it with a patch over one eye singing "dead man's chest".
Sure I'll help, but for now,
Just open the hood, go to the right side, you will see 2 tubes, one will have a small tube going into the engine about a foot from the car going forward. Those are the heater valve tubes.
You will see a interconnect piece between those tubes. that is the heater valve. You see the little piece that looks like a pendulum with a slot in it.
That is the link you need to pull and lock with a piece of wire. that will turn off the heater till you can get it fixed.
The dash is held in with two screws, one on either side of the defroster duct, and under the dash pad, there are 4 screws holding the bottom.
take out all the screws, and pull the dash pad straight back towards you and up a little.
It will come off with a little resistance.
Once you get it off, you can look down through the windshield, and on the left side of the defrost duct is the link that pulls the duct shut.
Get inside, sit in the driver's seat, you can pull the duct shut.
you can make a little holder from a coat hanger to hold the spring loaded valve shut. then most of the air will go through the front of the dash, and down on your legs. This will be enough air conditioning to get u through the summer.
07-25-2009, 07:44 PM
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You are moving here? oh Lordy..........
The heater valve thing is easy. you can do it with a patch over one eye singing "dead man's chest".
Sure I'll help, but for now,
Just open the hood, go to the right side, you will see 2 tubes, one will have a small tube going into the engine about a foot from the car going forward. Those are the heater valve tubes.
You will see a interconnect piece between those tubes. that is the heater valve. You see the little piece that looks like a pendulum with a slot in it.
That is the link you need to pull and lock with a piece of wire. that will turn off the heater till you can get it fixed.
The dash is held in with two screws, one on either side of the defroster duct, and under the dash pad, there are 4 screws holding the bottom.
take out all the screws, and pull the dash pad straight back towards you and up a little.
It will come off with a little resistance.
Once you get it off, you can look down through the windshield, and on the left side of the defrost duct is the link that pulls the duct shut.
Get inside, sit in the driver's seat, you can pull the duct shut.
you can make a little holder from a coat hanger to hold the spring loaded valve shut. then most of the air will go through the front of the dash, and down on your legs. This will be enough air conditioning to get u through the summer.
The heater valve thing is easy. you can do it with a patch over one eye singing "dead man's chest".
Sure I'll help, but for now,
Just open the hood, go to the right side, you will see 2 tubes, one will have a small tube going into the engine about a foot from the car going forward. Those are the heater valve tubes.
You will see a interconnect piece between those tubes. that is the heater valve. You see the little piece that looks like a pendulum with a slot in it.
That is the link you need to pull and lock with a piece of wire. that will turn off the heater till you can get it fixed.
The dash is held in with two screws, one on either side of the defroster duct, and under the dash pad, there are 4 screws holding the bottom.
take out all the screws, and pull the dash pad straight back towards you and up a little.
It will come off with a little resistance.
Once you get it off, you can look down through the windshield, and on the left side of the defrost duct is the link that pulls the duct shut.
Get inside, sit in the driver's seat, you can pull the duct shut.
you can make a little holder from a coat hanger to hold the spring loaded valve shut. then most of the air will go through the front of the dash, and down on your legs. This will be enough air conditioning to get u through the summer.
Thanks for the detailed instructions, I'm actually going to print them up and go outside and give it a try
