Air conditioning in 94 Toyota Corolla

My '94 Toyota Corolla (160,000 miles) runs great, however, in the warm weather at first when the a/c is on it blows warm air…If I park, do an errand, and make a return trip the a/c works fine…

Would anyone know why at first it blows warm and after a break (but within an hour or 2), it works fine? Does anyone have a recommendation for having it work well on the first trip?

Have you had the refrigerant checked in the system? Sounds like it might need a charge.

Thank you, I’ll have it checked.

If it cools just fine when it actually kicks in, I doubt the refrigerant level is low. I’d be looking for something like an electrical control such as a relay or sensor that doesn’t work when cold, but once the engine heats it up, it begins to function. It could also be the compressor clutch binding and not engaging until it heats up. Check connectors to all the sensors in the system. I’d have your mechanic check to see if all the pressure sensors are working, including your “clutch cycling switch” if your vehicle uses one.

I would almost suspect the cooling fan not coming on when first started thus no heat transfer off the condenser (is that what they call it) out front of the radiator. Some vehicles will not run this fan until the car reaches a certain temperature or a particular AC setting on the dash. Also the fan itself could be failing intermittently. I would just open the hood and see if it is turning when the non-cooling issue is happening.

We had a 90 Sunbird that would do this and I just replaced the fan motor with a new one from Advance Auto Parts. You could tap on the side of the fan motor with a wrench and it would start back up proving it was at fault.

Cooling Fan?? You mean the fan for the radiator?? How does that effect the A/C???

Yes the one on the radiator. It helps air flow across the radiator and condenser which aids in reducing the delta between the high side and low side of the AC system much like the exterior fan on a heat pump home heating system. Without that airflow the high pressure side will get too hot and then the low side will not be cool enough to tell a difference. You will reach the high side over pressure switch and it will disengage the compressor. I am not the best at explaining refrigeration theory.

Our Crown Victoria when placed on Max AC will always turn on the electric fan attached to the radiator. When on normal AC it will rely on the thermal clutch fan and normal air flow of course until the radiator temp gets hot enough. All manufacturers have a strategy for how they operate the AC for best performance.

We had a 01 Galant, AC cooled fine sitting still in park or neutral. Put it in drive and sit at a stop light the AC would blow hot. That was a battery that would not pass a load test. The radiator fan would slow down while in gear because Mitsubishi didn’t charge the battery when in drive and idle, at least that car did not. When the battery was weak not enough airflow.

Other issues could be the amount of bug/dirt buildup on the condenser or maybe even damage to fins on the condenser but that would be a cooling problem all the time I believe.

This is a can of worms best left unopened…Be thankful it works at all…But you can try this yourself…Before you start it first thing in the morning, open the hood and located the A/C compressor and radiator cooling fan. Start the engine, turn on the A/C and see if BOTH the compressor and fan are running. Look closely at the compressor to see that the center of the pulley is spinning, not just the outside part…