Here we go: 2002 Montero XLS, 94K, 4x4. Everything was working fine. Pressed the button to turn on the A/C...fan was blowing but no cold air. Checked the fuses under the hood. During operation of the A/C switch in the cab, I didn't hear the A/C compressor clutch engaging. Found the 25A fuse under the hood was blown. Figured it was the problem. Put in a new 25A fuse. Checked the power wire going to the A/C compressor and it had juice in it when the switch in the cab was on. Cleaned up the connector on the A/C clutch cause it was a little greenish, plugged the power wire back on the compressor, turned the A/C switch on.....nada. The fuse is still fine, just the compressor clutch is not engaging.

Figured maybe its a relay, but I can't figure out which one it is. Mitsubishi uses little symbols to distinguish their fuses and relays. I don't have a guage to check the high and low pressures. I was going to swap out the bad relay - if I can find it - and if that didn't work, off it goes to the shop. Any ideas which relay it might be, and maybe how much the relay costs and do I have to go to the dealer for this item. The 4 relays under the hood behind the fuses (which include the wipers and horn) all look the same and pretty much have the same numbers on them. I was thinking about swapping them out to find out which one was the bad one. Don't know if this is a good idea. Don't want to cause more damage. I don't know much about A/C system, so I'm hoping someone here does.

PLEASE HELP

Thanks in advance.

Jay

 

Check for power and ground at the a/c compressor clutch connector.

 

As per the last suggestion check the voltage at the clutch. If you can see the battery voltage going on and off with the A/C button then the clutch itself is bad. I just replaced mine two weeks ago. It's not an uncommon failure. Having the dealer replace it will cost you around $700.

The other thing you can do is buy a can of R134 with a gauge on it for $20. Hook it up to the low side and see if you have around 35-40 pounds of pressure. A lack of freon though usually causes the clutch to cycle on and off not simply never engage. That will at least let you know though if the system has a leak and has lost it's freon as well.

(2001 Eclipse Spyder 2.4L GS)

 

make sure you actually have refrigerant in the system.

 

no freon or very little freon in your a/c system will result in the compressor not coming on. assuming that the freon level is ok, you need to get a test light and make sure you have power and ground at the a/c clutch connector. if you do the clutch is bad. sometimes i have seen the clutch go bad and cause the fuse to blow. if you dont have power and the fuse is still good, the a/c relays are usually labled with a snow flake symbol. most relays in the fuse block are the same number, so u can swap it with another relay. just make sure its not the MFI relay. wont start if u put a bad relay in its place. good luck, keep us posted. greg....

 

many thanks to all, especially greg (jgbrules). Yes, if the freon level is low, the clutch will not engage at all. That's Mitsubishi's design. And yes, the four relays under the hood (wipers, horn, & snow flakes) are all the same. I swapped them out to test and all worked fine. So, summarizing the symptoms: No power in the wire to the clutch, fuse blown, clutch not engaging. All relays good. Replaced the blown fuse (25A). Even put a jumper wire from the clutch to the battery positive....nada!

So what's wrong. Took it to a really good shop I've been to before. Diagnosis summary: Low freon level. Started to fill it with freon and marking dye. Showed (could hear) a leak in the condenser. When they got to the condenser, they found that the condenser fan had failed and the blade is what made the hole in the condenser. The tech called me and said that, in addition to the condenser, I obviously needed a fan too. He said he called Mitsubishi and the condenser fan is just a crazy price from the aler - he said they want about $450 for a new condenser fan. The great team over there made some calls to a couple of local bone yards and were lucky enough to come up with a fan in good shape for $200. They couldn't get the fan till Monday, but the shop let me take the car home over the weekend (needed to make an airport run with lots of gear) &, and this is a big "AND", trusted me to come back to finish the work - didn't charge me a dime - I was already a few hundred bucks into the project. I plan to go back Monday to get the job finished. Expected final bill, new condenser, used condenser fan, freon, labor, etc,, about $1000.00. Thanks all! Hope this helps out the next guy.

 

Glad you got the problem resolved and the forum helped out. It's nice having a good group of people thinking of the problems we face in different ways. I've learned alot just reading the posts I don't have the knowledge to respond too.

 

Was the 25a fuse for the a/c fan?

 

NO a/c system on the planet will function if the refrigerant is low. they all have dual pressure switches (both too low and too high) to disable the system.

if there is no refrigerant in the system, the compressor will be destroyed as it will not be lubricated. The oil is transferred via the refrigerant in vapor form. No refrigerant = no lubrication, hence the systems will be shut off.

all AC systems have been like this for decades.

 

I know this thread is old, but I thought I'd give it a try since there's nowhere else to go or ask.
I have2006 Mitsubishi Galant 2.4L 140K miles and the a/c stopped working. I replaced the compressor, comdenser, expansion valve, all the o-rings, clutch relay and pulled a vacuum for 1 hour, refilled the low side to 40 psi of refrigerant and now there is no power to the compressor. There's power to the high side pressure switch and the relay. I'm not sure what's wrong, someone please help.