Hello - I have a 98 Montero Sport. Yesterday morning my AC blew cold as it always does. I commute 45-60 each way in Dallas traffic and it always blows cold even in July heat. Yesterday when I left work I noticed it was not blowing cold. It felt like it was blowing the same temp as the outside temp. I checked the fuses and they were not blown. I had the A/C condensor, receiver dryer, evaporator core, and expansion block changed out 4 years ago to the tune of $1300. The car is not behaving the same way it did that time. (I have had other cars with slow or fast leaks and you can generally tell when it is going to go out. That time it had lots of leaks and would initially blow cold and then get hot.)

I made the mistake of buying a Chilton subscription only to find out that they don't have any A/C info for my vehicle. There is some note that AC repair should only be performed by a certified tech. I just wanted something to help me know what might be wrong so I don't get ripped off at the repair shop. Chilton is a ripoff. I'm trying to educate myself before I go to the mechanic.

Any ideas what might have caused the previously great running AC to just stop one day?

Thanks,

Blackcloud

Well welcome to teh forum , and yeah sorry about that Chilton online crap , they always seem to have sum **** gimmick up their sleeves. First i would say is does the a/c light come on when yu turn the a/c on , if so , does it go off when pressed off . if teh light constantly stays on wether pressed or depressed there is an issue with the a/c control head . If the light does not come on wether pressed or depressed with teh system on there is a system issue , typically an a/c line pressure sensor or pressure malfunction .

Okies if the switch comes on look to see if the compressor comes on , in which it most likely is not. In which case it is usually good to have a/c gauges and manifold set. This way yu can check the system pressure to see if there is adequate pressure in the system.

if yu notice that the compressor appears to be on but still it is not blowing cool air , it is most likely that there is an issue with the compressor. Altho teh clutch of the compressor has engaged , the reciprocating shaft inside the compressor is likely broken , and is not compressing and pumping the a/c refrigerant. The chances that teh a/c control head temp setting is malfunctioning is very unlikely , as for it would erractically alter the temp setting and not just be at a constant ambient temp.

If the system has a adequate charge of refrigerant , , the low side connection will show anywhere frum 6-10 BAR of pressure (88-145lbs) is adequate for the system to operate.(this is the standing system pressure , gauges just hooked with vehicle stopped, a/c running it will fall to 35-40 lbs with compressor on) if there is adequate system pressure , and the a/c compressor clutch does not engauge , the low or high side pressure switch is suspect.

The low and high side system pressure switch help the a/c compressor to operate when the system pressure is compatible with settings. If the low side pressure is to low (not enough refrigerant) the switch will render the compressor inop until there is enough in order not to damage the compressor of running in a "dry" state with n o charge . The high side pressure switch , located on the dryer , reads the high side pressure. If teh pressure is too great on that side the high side pressure switch shuts off the compressor. Most import systems just have a high side multi function switch located on the dryer.

With the system on , unplug the pressure switch and check for incomming continuity , if there is none , there is a continuity issue elsewhere , the control head or burned under hood fuse for the a/c compressor . If there is incomming continuity , the pressure switch is likely bad.

I had a similar condition in my '95 LS, but my a/c quit while I was on the highway.
I feared the worst, but it turned out to be a $40 expansion valve which was 1/2hr to an hour repair.

No guarantee that's your problem, but it's somthing to consider. Looks like Rockauto.com has your valve for <$20.

The expansion valve/drier has the pressure switch on it. Hard to believe tho , that its that . Unless yur referring to the pressure switch to the expansion valve. If the expansion valve/drier would have to be all of a sudden restricting pressure , making the discharge line(high) pressure really high and the switch wut disable the a/c compressor . If the ex valve drier were have an issue yu would have erractic a/c issues.

Thanks for the replies. I was going to check the refrigerant level when I had to check to see if the compressor was running. DUH. I did not even need to go as far as checking the refrigerant. It turned out that the AC belt was broken and the other 2 belts by it were about to go to. I had the belts replaced and the AC resumed running at its normal condition.

thanks again

Awsum deal.