Blown cab a/c fuse

[ports]

On my way down South 2 weeks ago, I noticed when turning on cab A/c that little green light did not come on as did not A/c.  Didn't use motorhome last year but year before hand refrigerant change and all worked well.  Anyway, when I got to my destination, I removed the glove compartment and checked the fuse.  It was blown.  Put new 10 amp fuse in and put everything back together and when I turned on air light came on and then right off again.  Checked fuse I just put in and it was blown.  Like to fix this myself if possible.  Anyone have any ideas what and how to check to locate issue.  Thanks Ports

[ports]

Sorry!  I didn't realize that I sent the same message several times.

[linda s]

I can't delete individual posts, only whole threads. But you can. Just go to the extra post, click on the 3 dots on the top right and it will drop down where you can delete that post. 

Linda S

moderator

[thewanderlustking]

Either there are a bunch of posts and responses missing from this thread, or an identical thread was posted up a couple weeks ago?  I’m confused as I can’t find that other thread. 
 

Anyways, the most likely issue is a bad ac clutch, or a locked up compressor. The OP for the other thread (I believe) had a 3.0 engine. 

Typically, ac clutch replacement is a replace the whole compressor job.  I say this as this is where many shops stop with the diagnostics.  A locked up compressor or a bad clutch both mean replacement of the whole thing. 
 

Some can be done in truck without pulling the compressor, but some special tools “may” be required.  On a 2.4 engine this should be doable for a decently skilled DIYer. On a 3.0, I wouldn’t do it in my driveway and I would be replacing the whole compressor. 
 

If you have an 80’s era truck, it originally had R12. Most have now been converted to R134a. R12 systems did not have barrier lined ac hoses as the molecules are bigger. R134s has smaller molecules and needs barrier hoses and utilizes different fittings. An R12 system filled with R134a will frequently leak out in  as little as a year or less. 
 

The required changeover to R134a was in 1996. In my experience most manufacturers complied around 1990.
 

There are tests one can do to narrow  it down for sure. The simplest is to see if your compressor is locked up. You need to try to spin it by the clutch If you can’t spin it by the clutch, compressor is bad. If you can, measure the resistance of the coil. 
 

Even quicker.  Replace the fuse. Turn the ac off. Start the truck let it run a minute. Have somebody turn the ac on while you watch the compressor. If the clutch engages, the truck bogs down and then the fuse blows and truck goes back to normal, compressor is locked up. If it blows cold for a moment, compressor clutch kicks in and rotates with the pulley for more than a few seconds, THEN the fuse blows, bad clutch. And you can verify that by measuring the coil resistance. 

Edited October 7, 2022 by thewanderlustking