AC system keeps popping fuse....

[Doc Holiday]

I took the truck in to have the AC system charged after a complete system rebuild. Everything (yes everything) was replaced. The tech vacuumed the system down and it held. After he filled it and pressed the button "it popped the fuse three times". He evacuated the system and they called and said they couldn't fill it. I brought it back and tried to diagnose it but can't get it to pop a fuse at all. I pulled the compressor wiring and plugged it back in, nothing seems to make it pop.

The following is the list of parts replaced.

Condenser
Transducer
Compressor
New compressor wiring on the engine harness side
All of the lines
Evaporator
Drier
Heater core
Blend doors
Fan clutch was swapped from electric to a mechanical


The only thing I have wrong with that system right now is the blower only works on high

 

[petersonj]

I have more questions than answers.

Was the air conditioning working before you replaced all of the components?
Was the fuse blowing problem happening before the AC work was started?
Did you replace all of the components that are listed and have a shop pull a vacuum and recharge? Or, did you have the shop do all of the work including the vacuum and recharge?

He evacuated the system and they called and said they couldn't fill it.

Why couldn't they fill it? If the truck was returned to you with no refrigerant installed, the compressor will not get a signal to turn on. That could be why the fuse won't blow now.

- John

 

[Doc Holiday]

Was the air conditioning working before you replaced all of the components? Nope, hadn't worked since Father's Day of 2017 finally replaced all the parts this spring

Was the fuse blowing problem happening before the AC work was started? No it worked fine prior to the compressor going bad because the fan clutch was junk

Did you replace all of the components that are listed and have a shop pull a vacuum and recharge? I replaced all of the parts, they pulled the vacuum and charged it

Why couldn't they fill it? They did fill it but when it wouldn't "run" without blowing a fuse they evacuated all of the refrigerant

If the truck was returned to you with no refrigerant installed, the compressor will not get a signal to turn on. That could be why the fuse won't blow now.
That was my guess too, for some reason he assumed I would need to replace something and evacuated it.

 

[petersonj]

Which fuse is blowing? There are two fuses associated with the AC compressor clutch relay - a 7.5 amp PTC fuse for the relay coil, and a 10 amp fuse for the relay contacts.

- John

 

[Doc Holiday]

The 10 amp in slot 16

I haven’t seen a 7.5 amp fuse anywhere

 

[petersonj]

According to the 2003 air conditioning wiring diagram it appears that Fuse 16 (10 amp) supplies voltage to the switched part of the AC clutch relay. When the contacts close, then voltage is supplied directly to the AC compressor clutch. I would bet that if you jumpered terminal #30 and #87 of the AC relay that the 10 amp fuse will blow. If you perform this test, make the test brief as there is no refrigerant in the system.

If the fuse does blow, try disconnecting the AC compressor clutch wiring at the compressor. If the fuse still blows, then the problem is likely associated with the the wiring harness replacement work that you did.

Note: The diagram below is actually a 2004 diagram, but should be similar enough for troubleshooting. I was not able to copy the 2003 diagram.

- John

 

[Doc Holiday]

According to the 2003 air conditioning wiring diagram it appears that Fuse 16 (10 amp) supplies voltage to the switched part of the AC clutch relay. When the contacts close, then voltage is supplied directly to the AC compressor clutch. I would bet that if you jumpered terminal #30 and #87 of the AC relay that the 10 amp fuse will blow.

If the fuse does blow, try disconnecting the AC compressor clutch wiring at the compressor. If the fuse still blows, then it likely associated with the the wiring harness replacement work that you did.

Note: The diagram below is actually a 2004 diagram, but should be similar enough for troubleshooting. I was not able to copy the 2003 diagram.

- John

View attachment 128610 View attachment 128611

I wonder if it’s possible that I swapped the wires

 

[mwilson]

Or you may have a defective clutch.....