My Air Conditioner In My Chevy Truck Is Not As Cold As It Should Be

Reader Question Hello Austin,

I have a 1990 Chevy truck 4×4, 5 speed, 4.3 engine. I cracked off my hi pressure switch, the a/c worked for 2 days then stopped. i took it in and they replaced it with an after market one, it has 2 wires on it , but they hooked up one cause my old one only had 1 wire.

I took truck home and the a/c quit working. i took it back for a compressor and it was making a noise, so they changed it out for me. but they can only get 1.5 lbs of freon in it.drove the truck home and within 4 hrs, the compressor was turning on and off, cause it was loosing freon.

So I took it to another mechanic and he checked it with a Geiger counter, and found a leak at the bottom of evaporator. so i took it back to the shop that changed compressor. it lost .8 of the 1.5 lbs of freon.

So they filled it back only to 1.25 lbs this time. when i revved the engine they got anther .5 lbs in system with dye. and their was no leaks with the geiger counter and the infer red lite.

I took it for a ride and came back and still no leaks could be found. it is only blowing 62 degrees now. on the 2nd compressor it was blowing 38 degrees unless their thermometer was wrong , cause it didn’t feel like 38. but it feels like 62 now.

Before i cracked the high pressure switch when i put the fan on medium or high it would kick up to a higher speed on its own for about 5 minutes until the cab cooled off, then it would drop down to its normal speed again. and now it doesn’t do that it just stays on where i put it it doesn’t change any more. why?

My ac evaporater drains out alot more water now too. i had my truck for 10 yrs and it always left a puddle about 12 inches, but now its about 3 feet of puddle. why? and why can,t i get 2.8 lbs of freon in it now.

Before it broke i had 2.5 lbs of freon and it was blowing at 48 degrees. because i cracked the high pressure switch and ran it for 4 days my a/c system is falling apart. i have $850 in it already and if its the ac evaporater thats anther $ 600. so how do i get more freon in it. nothing is leaking now but its not as cold as it was. what should I do.

I don,t want to sell it cause every is new on it and i love my truck. its like brand new. i don,t think they are tring to rip me off , cause they would have wanted to change the evaporater.

When they throw water on the grill it brings the pressure down on the compressor also, thats why they told me i needed a compressor in the first place and they said it was running to hot. are they lying to me. they also changed the filter it had some metal shavings on it. the 2nd mechanic said they screwed up my 1st compressor with the vacuum cause they left it on system for 30 minutes and sucked the o rings out.

when they changed my high pressure switch.. they never changed my dryer either because they said the nuts were to tight.they didn’t want to ruin the evaporator. thats my story now what do i do. i was thinking of adding a can of freon myself.

Yesterday my ac compressor was turning on and off , today its not. now its blowing harder out of drivers side 2 vents than the passengers side. could it be an electrical problem in the circuit board behind the switch on the dash? or the blower motor or the vent door?
help me .. thanx

Hey Jeff

I would suspect you are sucking in FRESH HOT air, which is obviously harder to make cold than RECIRCULATED air. Make sure the control head settings are set to RECIRC or MAX, make sure there is NO outside air getting into the evaporator case…like from a hole under the hood at the dash that is allowing HOT air from the engine to get inside the evaporator case, and make sure your heater control valve is shut OFF.

One heater hose under the hood should be hot the other hose should not be, if it is your heater core is HOT with coolant and will not allow your ac to get cold. You can take a pair of vise grip pliers and block off your heater hoses and drive the truck to see if that helps make the ac colder. It will NOT cause the engine to overheat with the pliers blocking off the heater hoses.

The air being stronger on one side than the other…there was probably a problem with the evaporator case installation and its blocking off the air duct, restricting the flow. More condensation water on the driveway tells me there is too much humid hot air inside the evaporator case…probably because it is not sealed correctly or the heater is ON.


Austin Davis

Posted in: A/C and Heating

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