Questions and Answers

Dodge Dakota A/C Cuts Out Q. This truck is not always used every day of every week and then only for local driving. Every other weekend it travels 250 miles round trip at high speed. The A/C would just stop blowing cool air. If I shut the A/C off then turn it back on it would work. I had it checked twice and they couldn't find anything wrong with it. They put some dye in the system after the second check up.

I took it back two or three weeks later when it acted up again. The dye check showed a hole in the evaporator. They replaced the evap, dryer and orifice and recharged the system. It worked great the next day on the first leg of the long weekend trip, however, on the trip home about an hour and half into the drive it started the same thing as before. I shut it off for a minute or so, turned it back on and it was okay.

I called the auto shop and they are confused as to what to check next because it was working fine. They thought maybe something might be wrong with the electrical since the compressor comes back on when I shut it off and turn it back on again. Do you have any suggestions as to what they should look for? Appreciate any help you can offer.

• 1999 Dodge Dakota Club
• 3.9 liter V-6
• Automatic transmission
• 19,501 miles
• Fuel inject
• ABS, P/S, A/C, Cruise control
• Rack & Pinion steering

Thanks...

A. This is going to be tough to locate, but I think I know a way of determining what's going on. We'll have to fabricate a little test box to do it.

In essence what we need to do is monitor the A/C relay. We need to tap into the A/C relay feed wire at terminal 86 of the A/C relay. Hook up a small bulb to the tap and just run a ground for it. Make the wire long enough to reach inside the cab so you can see it.

The next time the A/C cuts out, see if the bulb is still lit. If it is, then you know everything up to the relay is fine. If not, the problem is between fuse 7 and the A/C relay. If the light stays lit, move the tap to terminal 30 of the A/C relay.

Same thing, if it cuts out and the light stays lit, everything up to there is fine. If not, the problem is between fuse E in the Power Distribution Center and the A/C relay.

Doing the same checks at terminal 85 and 87 of the A/C relay will confirm if the relay itself is okay or not. If the light stays on at terminal 85 of the A/C relay that will indicate the wiring between the A/C relay and PCM and the PCM itself is good.

The only things we can't check in this manner is the high and low pressure switches. As soon as the compressor shuts off, the pressures will stabilize and the switches will close. You can check to see if you lose power at the light green/white wire with our home made tester. That will tell us that power will be at the switches or not.

I think you'll find the problem is probably with the A/C relay or the Low pressure switch.