91 Corolla Variable A/C Cooling

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  #1  
Old 07-30-06, 02:21 PM
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91 Corolla Variable A/C Cooling

My 1991 Toyota Corolla has it's original A/C system, with the
"old type" of refridgerant, R12.

Recently it shows this problem: after perhaps 30 to 60 minutes of blowing cold air, it slowly loses it's coldness until it's blowing non-cooled air.

Once in a while, if I just leave the system on, the cold will return for awhile. I can also sometimes get it to blow cool air again if I turn off the compressor for 10-15 minutes.

I am not going to attempt at DIY repair - this is out of my league, but I'd be grateful for a tentative diagnosis from the air conditioning experts here.

Dave
 
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  #2  
Old 07-30-06, 02:38 PM
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check all electrical conections to any part of the a/c especially the compressor and refrigerant canister. if nothing else, it's electrical and you need to take it to either be recharged or repaired
 
  #3  
Old 07-30-06, 02:59 PM
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Join Date: Jan 2005
Location: Sterling Heights
Posts: 308
Originally Posted by Floridian
My 1991 Toyota Corolla has it's original A/C system, with the
"old type" of refridgerant, R12.

Recently it shows this problem: after perhaps 30 to 60 minutes of blowing cold air, it slowly loses it's coldness until it's blowing non-cooled air.

Once in a while, if I just leave the system on, the cold will return for awhile. I can also sometimes get it to blow cool air again if I turn off the compressor for 10-15 minutes.

I am not going to attempt at DIY repair - this is out of my league, but I'd be grateful for a tentative diagnosis from the air conditioning experts here.

Dave
Dave,
When the air stops cooling, does the airflow out of the vents seem to be lessened? Also, next time it stops cooling, pull over, wait about 5 or 8 minutes, turn off the A/C and see if you get a big puddle of water under the car.

It's possible the evaporator is freezing up on you.... Do you live in a "High Humidity" region? If so, and you're slightly low on refrigerant, the evaporator could be freezing.

When that happens, generally you also lose some of the airflow through the ducts because the ice clogs the evap and blocks airflow.

If you live in a high humidity climate and are getting the puddle of water under the car when you turn off the A/C and you're losing some airflow when it stops cooling; my bet is a slight, low charge on the refrigerant!

Another thing to look for is if the compressor disengages when it stops cooling. That would be an indication of a different problem; but I'd need more info to determine why!
Good luck,
Phil
 
  #4  
Old 07-31-06, 02:03 AM
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Join Date: Nov 2001
Location: North Texas
Posts: 2,345
evaporater froze

Sounds like the evaporater is frezzing up the because you are low on freon.
Next time try this when it blows hot shut off A/C and use the vent on outside air mode to thaw it out. try it for about 10 min and then try air again.
You will be forcing outside air over the evaporator to thaw it out,
 
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