help with ac on 94 silerado

[yourkiddin]

my truck wasnt blowing cold air. got a can of freon that had test tube gauge with it. it was low and the compressor wasnt coming on. while filling it the compressor came on and was blowing cold air. lasted two days, now nothing. it still test good on pressure and the compressor comes on and then shut off repeatedly. i dont have all the right equiptment and dont want taken at a shop. any quick things i can do to test the compessor or any sensor i can look at ?

 

[TilliamWe]

Re: help with ac on 94 silerado

compressor engaging and disengaging all the time is the #1 sign of low freon. You sure about that second pressure test?

 

[SS MAYFLOAT]

Re: help with ac on 94 silerado

If your system has such a leak that all of it leaks out. Just adding freon to a system that is completely out will not work for long due to non condensibles in the system such as moisture and air. The system needs evacuated (vacuum) to get the air and moisture out. However unless the leak is found and repaired, pulling/evacuating the system is only going to introduce more contaminates to the system not allowing it to perform.

There should be a sticker/lable that will give the capacity on how much the system holds. Too little or too much the system will not work like it was engineered to do.

 

[Rocky_Road]

Re: help with ac on 94 silerado

compressor engaging and disengaging all the time is the #1 sign of low freon. You sure about that second pressure test?

Got to be careful about this analysis...trucks during that era had a goofy environmental switch that would cycle the compressor without any regard to pressures. My Silverado would do this without any rhyme or reason, and only quit when I replaced the compressor with one that didn't accept the two wire plug that would trigger this.

Happy boating!

 

[j_martin]

Re: help with ac on 94 silerado

They have a leak detect refrigerant that has a UV component oil in it. When it leaks you can see it with a black light. Put a can of that in, let it run for a day, then go at it with a black light.

Fix the leak, which could be anything from a rusted out condenser to a loose fitting, then it needs to be evacuated to a high vacuum, both to verify the fix and to pull all moisture and air out of the system, and recharge.

If it were mine, I'd put 8 oz of propane in it, look for the leak with bubble soap or a flammable gas detector, fix it, evacuate it with a high vacuum pump, (25 micron, $150, Harbor freight, Robinair dual vane ripoff, works good) and charge it with a mixture of 70% propane and 21% isobutane. (one can each of Coleman propane and ISOheat mountain stove fuel)

Just did that to a 90 Dodge van that hadn't been cool in years. Had a damaged hose. Now you can hang meat in it. It was so wet the fittings were beginning to rust inside. Total cost just over $200, and I now own a $150 vacuum pump that has a lot of uses. Shop wouldn't look at it for less than that.

 

[yourkiddin]

Re: help with ac on 94 silerado

Thanks for The suggestions.

 

[Boomyal]

Re: help with ac on 94 silerado

They have a leak detect refrigerant that has a UV component oil in it. When it leaks you can see it with a black light. Put a can of that in, let it run for a day, then go at it with a black light.

Fix the leak, which could be anything from a rusted out condenser to a loose fitting, then it needs to be evacuated to a high vacuum, both to verify the fix and to pull all moisture and air out of the system, and recharge.

If it were mine, I'd put 8 oz of propane in it, look for the leak with bubble soap or a flammable gas detector, fix it, evacuate it with a high vacuum pump, (25 micron, $150, Harbor freight, Robinair dual vane ripoff, works good) and charge it with a mixture of 70% propane and 21% isobutane. (one can each of Coleman propane and ISOheat mountain stove fuel)

Just did that to a 90 Dodge van that hadn't been cool in years. Had a damaged hose. Now you can hang meat in it. It was so wet the fittings were beginning to rust inside. Total cost just over $200, and I now own a $150 vacuum pump that has a lot of uses. Shop wouldn't look at it for less than that.

jmartin, you sayin to charge the A/C with propane and isoheat?

 

[Nandy]

Re: help with ac on 94 silerado

Yourkiddin, when you are reading the gauge make sure you are reading it when the compressor is ON. That is the correct operating pressure reading.

 

[Nandy]

Re: help with ac on 94 silerado

jmartin, you sayin to charge the A/C with propane and isoheat?

Yes, that is what he is saying. This is done in many countries and done properly it is not more dangerous that driving a car with 16 gallons of gasoline. Problem is in the good ol USA no ac technician will touch your system if they find that you have that mix of refrigerants.

Jmartin, how do you charge the system in the sense of getting the connections between the propane fuel and the ac manifold? Is that a home made connector or is there is actually a connector adapter for that?