Can't figure out my AC issue

[chrluc]

Have a 96 EB 4.0 the AC is hot. The compressor will not run but runs great when connected to the battery and AC is nice and cool. I have checked the fuse and relays (unless the is one I don't know about) Jumping the low pressure switch does nothing. I'm not sure what else to check. I have heard that jumping the high pressure switch is good to try and then other say absolutely never jump the high pressure. Anyone else have any suggestions I can try?

 

[1997XLTRollover]

Do you have enough pressure in the system? low pressure will cause it not to run.

 

[masospaghetti]

I would try jumping the high pressure switch. Just check to make sure its not dangerously overcharged first. Its purpose is to make sure the system isn't overcharged.

Do you have the manual AC controls or the automatic climate control?

 

[chrluc]

The system was charged, and pressured up. I have the automatic climate controls. and the AC blows warm when connected normally, but blows cold when connected to the battery. Could I be missing a fuse or relay?

 

[1997XLTRollover]

Mine does the same thing. If I force the compressor on ac is killer. If not it won't run on its own. It kicks on, kicks off, kicks on, kicks off every 2-3 seconds.

 

[429CJ-3X2]

When I bought my '01 Sport Trac, the a/c wouldn't kick on. I checked the pressure switches and found the o-ring on one of the connectors had gotten down into the top of the switch preventing a proper connection. Pulled the o-ring out, plugged in the connector, and had a/c!

 

[bobflood]

The system was charged, and pressured up. I have the automatic climate controls. and the AC blows warm when connected normally, but blows cold when connected to the battery. Could I be missing a fuse or relay?

There is a relay (small black rectangular box) on the circuit board in the automatic control head unit that activates the compressor clutch. The solder connections can degrade; you can measure the voltage coming out but it won't pass enough current to activate the compressor clutch. You have two choices - you can pull the head unit, disassemble, and resolder the joints, or you can order a rebuilt head unit for about $100 online. I resoldered - was easier job than I thought. Good luck.

 

[koda2000]

There is a relay (small black rectangular box) on the circuit board in the automatic control head unit that activates the compressor clutch. The solder connections can degrade; you can measure the voltage coming out but it won't pass enough current to activate the compressor clutch. You have two choices - you can pull the head unit, disassemble, and resolder the joints, or you can order a rebuilt head unit for about $100 online. I resoldered - was easier job than I thought. Good luck.

+1 on this problem and fix. Seems to be a fairly common issue with the EATC.