2000 Dodge Dakota 4.7L V8 212,000 miles. I had trouble with my AC this summer. The AC would work when I first started the car after it had been sitting for several hours. After I ran it for about 15 minutes the air got hot. I checked the freon and it was full. I checked it out and found that the clutch on the compressor would disengage when the air got hot. I replaced the clutch relay but that did not fix it. I spoke with an AC guy and he said that he thought the air gap on the compressor was getting out of whack when the compressor got hot. Sounds odd to me that it just now did it after 200,000 miles.

Now since it has gotten cooler the heat works, but it seems to just get warm. The engine can be close to 210 degrees but the heat is just warm. The heat went from warm to hot after the engine ran for about 15 minutes. I moved the heat control **** from hot to cold and the air got cool, then got warm again after turning it back to hot.

This summer I also noticed for the first time ever that the air coming from the vents smelled very musty and had a mildew smell after running the AC (for the short time that it works).

Any ideas or suggestions would be helpful. Not sure if the evaporator has a problem or not. Would that cause the clutch to disengage?

 

I am no AC tech by any means and I have a 3.9, not a 4.7 but I will guess at this one. It sounds to me like the AC either has a leak somewhere and is losing freon or the compressor is bad. A shop can do a real diagnostic on the AC system and tell you for sure. They can inject dye into the AC and find the leak, and there are sniffer tools they can use to check for leaks too. If I had to pick one or the other, I would say you have a bad compressor. Now that the weather is cool outside they may have a hard time getting the AC to cycle, but they should be able to find the problem. When my own AC compressor had problems (my AC worked OK but the compressor was very noisy) I had a shop evacuate they system for me then I bought my own new compressor at Napa, I bought a new accumulator-drier at Carquest and had to buy a new fixed orifice tube at the Dodge dealer and I did all the work myself. Then I just had the shop refill the freon. I saved about $500.00 by getting my own parts and doing the work myself.

The heat not getting hot is a pretty common problem on Dakota's, no matter what engine you have. The heater core is probably plugged. They are sort of known for the antifreeze to turn to jelly inside the heater core, especially if the antifreeze is not flushed and refilled on a regular basis.

If you haven't done a flush and fill on the antifreeze, now is a good time for it. You can also back-flush the heater core by disconnecting the heater hoses under the hood and using a water hose to run water through the heater core. Then change the water hose to the other heater hose and run water through it in the opposite direction. Each time you do that you should see a bunch of gunk come out the other heater hose. Flush it all out for a good 10 minutes and then reconnect the heater hoses, refill the antifreeze and the heat should go back to normal output and temperature. If the antifreeze has not been flushed in a while, it's a good idea to use one of the chemical flush fluids and flush the radiator and engine out too before you finally add the new antifreeze to the engine.

Jimmy