I have a 2002 dodge ram 1500 air cond. Problem. With air turned to max cool at idle it puts out hot air. When I drive it cools slightly. I charged the system myself about a year ago. Very cool air at first. About a year later it got warm again, I charged it again but it wouldn't take much coolant,seems to be full. Now it remains hot unless I drive down the freeway at 60.it cools sightly. Also at night while driving it acctually gets very cool. Does anyone out there relate to any of this?

A bad compressor will normally show the inability to generate enough suction and pressure at idle speeds. If the engine speed needs to be increased substantially to bring pressures in range, it's a sign the compressor is weak. The typical complaint is, "It only cools when the engine is revved or when driving down the road." It's often simple. If we hook, for example, the gauges up and see 80 psi on the low and high sides and the compressor hub is spinning, the compressor is shot. It's not producing suction or pressure. We could add more refrigerant and nothing would change. Compressors must be able to pull a vacuum and create pressure.

A/c cools when driving but warm when at idle... why

While charging a/c the low side read 45-55 and high side read 450psi why?

What's the purpose of the high pressure switch on my 2002 dodge ram 1500

What does a high pressure switch do

If your A/C is only working when above 20 mph check fuse number 39 should be a 25 amp on 2002 dodge ram 1500 3.7L if that's good turn your A/C on full blast and see if your condenser fan (small fan next to fuse box) is running it should run non stop when A/C is on if not running replace the condenser fan. Check eBay they are from $75.00 to $190.00 a lot cheaper than parts stores well here in NY.

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Originally Posted by Fear09

What does a high pressure switch do

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The high-pressure cutout switch serves 2 purposes.
1) It kicks on the high speed fan when the pressure gets sufficiently high.
2) It cuts off the compressor clutch just before the refrigerant is about to discharge from the relief valve.

Quote:

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Originally Posted by Fear09

A/c cools when driving but warm when at idle...why

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If your A/C is only working when above 20 mph check fuse number 39 should be a 25 amp on 2002 dodge ram 1500 3.7L if that's good turn your A/C on full blast and see if your condenser fan (small fan next to fuse box) is running it should run non stop when A/C is on if not running replace the condenser fan. Check eBay they are from $75.00 to $190.00 a lot cheaper than parts stores well here in NY