a/c gurus

[Stillstrokin8]

Alright a/c works great except at idle.... at idle it starts releasing out the relief valve... where is the high pressure cut off switch located? I've been told it will speed the fan up to keep from high pressures on the high side

 

[Gary]

It's either overcharged or the condenser is not doing it job. If the condenser fins are cover with debris or full of dead bugs air can't get through it to properly cool it, when that happens head pressure goes up, and it can go way up. So the first thing to do is a through cleaning of the condenser also make sure the inner-cooler and radiator are clear.

 

[Stillstrokin8]

It's bled off alot and will still do it so doubt it's over charged... and nothing looks dirty guess I'll just have to give it a good pressure washing... maybe I'll try removing the grill and taking it to the car wash ...trying not to replace the condensor... don't think it could be the high pressure switch? Read some where there's a switch that signals for the pcm to turn on the fan clutch

 

[04cr450]

could be a high pressure switch- doubt it though. Normally a high pressure switch fails completely meaning stays "open". the pressure switch opens on pressure rise, closes on pressure drop.

It could also be a clogged metering device. This would cause low suction pressure and high head pressure.. need to put a set of gauges on it and see what is happening. The guys above though probably have it correct with a clogged condenser coil, If it is clogged it cannot condense the hot gas to high pressure liquid, causing high head pressure

 

[Stillstrokin8]

So the fan shouldn't be coming on when the head pressure builds?