QuestionI have a '90 gmc Vandura 2500 with a 350ci engine and My Ac wasn't working I have a lifetime warrantee onthe compressor but they want $90 just to look at it So I purchased a retofit kit for 134a and was going to put it in but I decided to check the pressure on the system it said it was low about24lbs so I got some r12 sub and added it to system now compressor cycles on and off every 3-5 secs but the guage reads 30 to 50 as it cycles what am i missing is the switch on the low pressure side bad how do I test for it? or is the compressor bad? Test? I cannot seem to find anything specific in my Hasons repair manual Do you have anything specific for AC testing like a flow diagram for checks and tests? Also the air does not seem to be blowing cold while it cycles.
What to do? What to do? Thanks in advance for your valuable time BTW I build and repair computers so if I can help you in any way just ask! Retain my email for future use.
AnswerIf you had to add some freon to the system, this is usually caused by a leak somewhere in the system be it a hose or a component such as the evaporator, condensor or the compressor.
What I would suggest is that you remove all the R-12 from the system and when it's empty:
1. replace the orifice tube.
2. Add the correct amount or R-134 refrigerant oil to the system as stated on the package.
3. Evactuate all the air from the system via a vacuum pump.
4. Recharge the system with 2 cans of R-134a and check everything for leaks.
5. If no leaks found add the correct amount of R-134a per the instructions on the package.
6. Finish adding the additional amount of required R-134a freon to the system.
This should resolve your problem.
NOTE: Converting from the R-12 freon to the R-134a freon will decrease your cooling efficiency about 10% but I doubt that you will ever notice it.
Caution: do NOT add to much R-134 refrigerant oil or Refrigerant to the system. READ and FOLLOW the instructions EXACTLY.
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