Have had factory and add-on AC in cars from 1967 up. On those older cars, it was recommended that the AC always be turned Off when shutting down the car: the theory was that if left On, the compressor clutch would be energized when trying to start the engine, leading to more drag on the starter and drain on the battery.
Now, MOST cars are computerized and the systems don't engage the compressor until the engine is running. There's a remote possibility that your vehicle doesn't work that way - - - - or the electronic circuit disables the compressor during start-up and takes longer than it should to energize. Try turning Off the air on engine shut down and not turning it On until the engine is running . . . . a good idea even if that doesn't solve your immediate condition.
Some good replies I see here. I'll add that knowing whether or not the compressor is running during the faulty behavior is crucial. If the compressor is running the next step is to feel the suction pipe and see if it's cold, if it is cold start targeting controls such as temp blend door etc.
If the compressor is running but the pipe is warm, revisit refrigerant charge.
If the compressor is not running (assuming charge level is correct) target 'electrical' such as sensors (your words), pressure switches, clutch coil etc.
The only quirks I'm familiar with on Toyotas were Compressor Speed sensor failures (permanent no AC and blinking AC light) and Evaporator Temperature Probe faults (usually permanent no AC). Maybe others here know of one that fits that car?
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Hi U,
Although you provided some good info on the condition, Tony is right about needing year/make/model and I'll add that knowing if the car has manual or automatic temperature control will help too.
Specific YMM cars can have well known quirk that some folk may be able to cite right off the top of their head.
Just like your heater needs a bit of time to heat up, your A/C needs time to cool down, it isn't instant.
There is nothing wrong with your car. This is just the way things work.
First off... If the engine has not been run for several hours, or overnight, the engine is said to be COLD, not warm. You CANNOT expect IMMEDIATE cold air on starting the car under those conditions. The compressor has to build pressure in the system and get the refrigerant gases circulating before it will start to cool. This is normal.
I suggest switching the flow control to RECIRCULATE the air in the car. This will allow the AC to cool down faster. Also, inspect/replace the cabin air filter. A dirty or plugged filter will reduce air flow through the car and slow down the cooling.
a/c system has a pump, the pump must push the Freon around to get cold for your a/c to work.. so it wont work right away... will take a bit to get cold... the compressor has to turn fast to pump and get cold.. so at idle may take awhile.... it takes a lil bit to get cold to work. when you revv on it.. that's running engine faster which turns the belt faster thats wrapped around the compressor so the compressor is running faster meaning it pumps harder and faster....
it is possible the pump is weaker than it should be depending how long it takes it to cool off without revving on it...
make sure that the compressor actualy engages and is not short cycling... when its low on Freon it will short cycle on and off... make sure ur readings are around 40 psi.. the compressor should shut off about 32psi over low pressure.... when you check the psi pressure the compressor must be engaged and pumping....
it might also help if you put the very best Freon in... high dollar stuff... it is a huge noticeable difference if u have ever tested both kinds out.... it also makes a difference if the system was vacuumed down to remove air pockets too.
what is the year and kind of car?
are your cooling fans working and did you add feron?
and did you add the correct pag oil to the system?
I've had this problem for a while, when the car is warm, meaning not started over night or for several hours, the air conditioner does not blow cold air when I start the vehicle,
:the a/c switch is on,
:the temperature is on cold,
:I have checked for a paper blockage in front of the condenser
:I have checked the Freon level with a DIY refill can that has the gauge and it indicates normal (when a/c was engaged just because I was told that Freon would be low, which is not the case.
the a/c will blow warm until one of the following happen: I rev the engine for a few seconds around 2k rpm and release and it'll stay on at all times or if I start driving the vehicle and after about 30-40 feet of driving the a/c will start blowing cold.
I have changed the cabin filter every 15k miles as well. I feel like this is a sensor issue, any help would be appreciated, thanks
