Hey all,

It has been a while since I have been on this forum...

My A/C has gone out and I want to fix it myself.
(1998 Mustang GT 4.6 convertible)

The compressor pully is not turning when I turn on the A/C so either the compressor is shot or there is a relay that has gone bad...

Should I look to a relay first to see if that is an issue - or just assume that the compressor is dead and get a new one?

If there is a post somewhere that refernces my issue - that would be helpful as well.

Thanks!

ND

 

First off, do you hear the compressor relay clicking? It is located inside the passenger wheel well. If it's clicking, than you can safely assume that the dash controls are working.

If the compressor is not engaging- it could be because of the low pressure switch. If you get a leak- then that switch will prevent the compressor from turning on.

Before you decide to fix this- you will need to buy or borrow a set of gauges (for R-134a).

You need to do is figure out if there's any pressure and/or refrigerant in the system. If there's a leak- you can either use the refrigerant with dye in it OR pressurize it will an enert gas like Nitrogen and watch the gauges. Once you know if there's a leak or not- you can proceed to fix the leak and than evacuate and refill with refrigerant (R-134a on your car).

If you need to replace the compressor- you will need to remove the refrigerant that's in the system into a designated container. As long as your receiver/drier is working properly- you can safely reuse the refrigerant (it doesn't go bad). Plus, this way you don't have to adjust the oil level in the system either.

One last piece of advice- DO NOT OVERFILL the system with refrigerant. Because of the operating pressures of R-134a- it will not get as cold.

 

I checked the other day and ther is no pressure in the A/C line at all - used the screwdriver on the pin method...

So, the compressor will stop working if there is no pressure in the line? hmmmm - didnt know that...

I dont think I can just recharge the system though - dont I need an A/C vacuum to evacuate the lines of air or whatever is in there now?

 

Yes, you need to put the entire system into a vacuum. This allows you to easily pressure the system with refrigerant (eliminating any trapped air), and more importantly boils off any moisture in system.

Depending on your pump, I would evacuate it for at least 30 min.

 

Is there a way to try and jump the compressor so I can see if it even works and eliminate that as being the cause?

Maybe a picture of what I have to do or a pointing to an older post with the instructions would be helpful - thanks!

ND

 

On a side note - it is indeed hot in Phoenix. I flew in today en route to Salt Lake City and nearly passed out getting off the plane... I don't know how you guys survive 100F+ weather all summer.

Good luck with the AC, I know I couldn't survive without it!

 

My brother-in-law used to work at the Phoenix airport in the summer loading the planes with bags. He said that the fire department came out onto the tarmac one day and measured the temperature and their reading came back at 150 degrees!


Anyone have any ideas on the compressor jumping - it will be up to 112 on Saturday and I hope to have it fixed by then...!


ND