The A/C fuse (Fuse #17 which is a 20 amp fuse under the hood by the battery) keeps blowing when I turn on the air conditioning. My air conditioning had been working absolutely perfect up until a few days ago. While I was driving the A/C all of a sudden wasn't cold anymore although it was still blowing out room temperature air. I have tried several brand new fuses and it keeps happening. I just now replaced the A/C relay as well and my #17 fuse under the hood continues to keep blowing out.

When I replace the #17 fuse the A/C will work anywhere from a couple of minutes and sometimes up to 30-45 minutes before blowing. Does anyone know where I should begin troubleshooting after replacing the #17 fuse and the A/C relay?

I had a brand new a/c compressor, drier, and belt installed a few months ago. I have plenty of freon so it is defintely not a leak.

PLEASE enlighten me as to what I should check now...

 

That fuse feeds the compressor clutch coil (normally about 4 amps) and the condenser fan (maybe 10 or 12 amps normally) Check that the condenser fan turns freely by hand with the car off. Then unplug the compressor wire, start the car and A/C and see if the fuse holds. The fan will run but of course compressor won't engage and it won't get cold.

If it's not the fan, could be a defective clutch coil. Resistance through the compressor should be 3 to 4 ohms. Inspect the wiring, particularly where it goes under the pulley and the clips on top of the compressor for cut insulation and shorts to ground.

 

Hello,
I would agree with MK378 that you have a short in an wire some were. I have only been a member here for a short time, but from reading his posts he knows his stuff. I have been working on cars for over 40 years and I don't know everything and I'm allways learning.That is why I seak out these sites and try to post with any help I can give. Cars are not cheap to repair and any thing you can do yourself will save you money. Glad to have you as a member and hope you solve your problem. Please keep us posted on how the problem was solved we all want to know. Thanks 2010civiclx

 

Hello, mk378 and thanks for your reply. I tried removing the "Condenser Fan Relay" and the fuse # 17 will not blow when it is removed.

I have already replaced the “MG Clutch Relay" while I was troubleshooting and since the # 17 fuse is blowing only when the “Condenser Fan Relay” is in place then I am assuming you are going to say that my next step should be to purchase and replace the “Condenser Fan Relay” and see if the #17 fuse continues to blow?

I’ll wait for your reply and thanks again I extremely appreciate the help!




...And 2010civiclx, thank you for your feedback as well...much appreciated!!

 

When you remove the relay, the fan will not run. Blowing the fuse only when the fan is running could mean the fan is drawing too much current, or there is a short in the wires leading to the fan. Or it could still be a problem with the compressor and the combined current of the fan (normal) with the compressor (too high) is enough to blow the fuse.

Relays only switch the circuit on and off. A bad relay will not blow fuses. The problem is not the relay. If you really think it is, don't buy a new one just swap it with the rear defroster relay in the same box as they should be the same type. I can almost guarantee that won't solve the problem though.

If you have an amp meter that can measure 20 amps, you can test the draw of the compressor and fan by taking the relays out and connecting the amp meter to the contact points. Do this with the engine off. Never jumper anything to force the compressor on with the engine running. That can create a dangerous overpressure.

 

Ok well I'm glad I know that about how a relay cant cause a fuse to blow. I switched out the relay like you said and with a perfectly good relay placed in the fan relay position the fuse # 17 continues to blow.