WOT A/C relay problem

[Jeff673]

I had the accumulator/dryer changed due to a leak. The compresser was working ok for a few minutes then started cycling at low idle. At a high idle the comp stayed on and worked normally. I put a new WOT A/c relay in and it worked for about an hour while I drove home. When I got home, it started cycling again at low idle but works fine if I rev it up a little. I seem to think that maybe something is causing the Relay to overheat, or there is another sensor somewhere. Any help?

 

[Bob Ayers]

Bad TPS, or ECT sensor, telling the PCM the engine is too hot.

 

[Jeff673]

Thanks Bob, is there an easy way to check these?

 

[Quiksurf]

assuming your cycling issue is very short at high ambient temperatures .......

......the power feed into the relay is fed from the control head through the low pressure switch, through the high pressure switch and then to the wac relay. if you are loosing your power to the relay, then you could have a bad pressure switch, poor contact, low pressure, or a failing control head. if you keep the power feed and loose another part it eliminates the climate contol and now you know its more comlicated.

how does it cycle 5 sec on 5 sec off, 30 secs on 10 sec off?? what are your pressures like??? what is the temperature where you are checking it?????

 

[Jeff673]

the cycling is 2 sec on 10 sec off. It was about 95 deg yesterday. To make it more complicated. It worked fine when first started. After running for 10 minutes at idle it was blowing 46 deg F from center vents.

After swapping the Wac relay it worked for another 10 min. then the cycling again at idle.

At anything above idle it works fine and blows very cold, 38 deg F at hwy speeds, 95 deg F outside. I don't remember the high side pressure, the low side was 40 with compresser running. I'm going to check it again this morning and see what happens.

 

[Quiksurf]

2 sec on and 10 sec off sounds like a low charge with the 95F outside temp your highside should be 225 to 275?? give or take, but your low side should pull down closer to 25-30 when the compressor shuts off.

by the way off idle as in driving down the road???? did you check your fan??

 

[Jeff673]

The fan is working well. My idle was 650 rpm. I bumped it up to 800 and now the A/C works great all of the time. Blows 42 Deg F at idle on Max. Thanks to all for the input.

 

[Quiksurf]

tweaking the idle set screw in the throttle body can cause crazy symptoms sometimes, keep it in mind if you get idle or mixture issues later

 

[Jeff673]

I'll keep that in mind. So far, so good though.