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post #1 of 3 (permalink) Old 08-11-2019, 11:04 PM Thread Starter
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A/C and fans

When I turn on the air conditioner the radiator fans do not always turn on.
Sometimes they do and sometimes they don't. If the radiator fans don't immediately turn on when I turn on the a/c then I will get warm air coming out of the vents.
The engine is not overheating.
After several tries of turning the a/c on and off the fans eventually turn on and the a/c blows cold.

1. I checked the a/c and its fully charged
2. Both fans work when they do come on low speed.
3. A/C does blow cold when the radiator fans are on.
4. Checked the relays in the engine compartment fuse box and they visually look good.

I'm trying to understand why don't the radiator fans come on every time I turn on the a/c. This is an intermittent problem right now.

Is there anything else I need to check?

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post #2 of 3 (permalink) Old 08-11-2019, 11:28 PM
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Location: Fountain Valley California
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I do know that the fans will not turn on right away. The A/C system high side pressure has to increase up to something like 290 psi before they are commanded to turn on. Maybe your compressor is a little slow to ramp up towards its max output in a timely manner (at times). That would delay the rise of the pressure needed to request the fans to turn on.

An if the A/C high pressure line stayed just below the threshold psi for turning on the fans, I think the A/C would still be supplying you with some cool to fairly cold air, as long as the car was moving along at a nice pace (not so much sitting still).
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post #3 of 3 (permalink) Old 08-12-2019, 09:08 AM Thread Starter
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That sounds plausible. At the time the air temp was 80 degrees. Started the car and turned on the a/c. The air coming through the vents was warm. Drive at about 30 mph for a few minutes and the air is still warm. Stop the car check if fans are running and the fans are still not running yet.
Get in the car and get on the highway and get to 70 mph. The air coming through the vents is colder but not as cold as it should be. Turn on and off the a/c a few times the a/c is now blowing cold air. the fans are running.

This morning air temp is 72 degrees and start the car turn on the a/c and the air coming through the vents is immediately cold. The fans are running.
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