Tunz_Her

Hey there girls and guys

I am new member to the forum. I have searched but I have yet to find a post with the same issues as I currently have.

I have a 2008 Mustang

My a/c was working fine, then it just stopped cooling about 3 days ago. The blower motor still blew fine however it was not cooling. I then noticed that when I drove, the a/c got considerably cooler but when I came up to stop lights it would go back to blowing ambient breeze.

While coming to stops for a period of time, i noticed that the temp gauge would go to hot in a very short period of time.

Yesterday after disconnecting the low and high pressure switches and reconnecting, i started the car and the compressor clutch engaged right away. It worked fine for the remainder of the day. This morning, it would not engage.

I have checked my relays, fuses and compressor and they are all fine. Radiator fan is also fine. I just checked my ac pressure and got a high side reading of 240 and a low of 35.

Yes I am a somewhat technical chick however I live on the island of Mayaguana in the Bahamas and I do not have ready access to a a/c specialist or shop.

Any help to resolute would be greatly appreciated.

jwog666

does your radiator cooling fan come on when u turn on the ac? if not that is your issue, the fan needs to run to cool the engine and for the ac to work when not moving down the road

Tunz_Her

Thanks for the reply. Yes it does come on without issue.

jwog666

because both systems are not working correctly, im thinking that airflow over the radiator and condenser is your issue, check for any blockages of airflow , sometimes debris will build up between them

Tunz_Her

There is no debris blocking. Already ruled that out.

rsfdiver

The a/c compressor will automatically turn off when the engine overheats as a fail safe. The radiator fan is the most likely the culprit, or possibly the relays #25 and #28. When it does it again stop forward progress and see if the fan is running. Last time it happened to us we changed the water pump, thermostat, swapped around relays, replaced relays to no avail. Changed the radiator fan and it seemed to work OK for 4 to 5 years and am now having the same issue. So when it over heats (indicated by no cold air from a/c) I'm gunna hop out and see if the fan is running, It should automatically come on when a/c is turned on, wiggle the relays check the 40 amp fuse (#3?)...
It's been suggested to check for water in the oil which would indicate a cracked head gasket which could introduce gasses into the cooling system but I'm betting the fan just stops working sometimes.

Chromeshadow

I think rsfdiver is on the right track, if the cooling system is not working correctly the AC will not work.
I'm assuming your weather is hot and humid-it's really working your cooling system. The AC should work OK when your car is not overheating, so you could have more than one issue. If the AC is working extra hard it may be enough to cause your car to overheat in your weather.
I would start with the cooling system-does your car only overheat when stopped or running in stop and go traffic? This is usually a fan issue. Our fans usually shut off when we are driving over 40 mph-there is enough airflow without the fan to keep the engine cool. If it overheats over 40 mph it may be more serious than a fan. I would and check for bubbles in the overflow tank-which could indicate air being pushing into the cooling system from a cracked head. You might have a hose collapsing or a temperamental thermostat. The first this I usually do is replace the thermostat, I have had a couple of cases-when the car overheated for any reason-then the thermostat started causing problems.
Good luck finding the problem. Btw-it might hit 70 here for Jwog and all of us in WI, we'd like to trade our weather for your overheating problem!

jwog666

hey now lol. my car likes the cold dense air, aside from the pesky snow that keeps me from driving 5 months a year or so.

Derf00

When was the last time the coolant was replaced? Old coolant loses cooling capabilities and during hot, hot/humid month you could be overtaxing your cooling system as mentioned. This will shut down the AC when things get too hot.

Our fans are dual speed and controlled by the PCM. Do you have a tune for the car? Who's it from? For Example the Bama tune from American Racing lowers the temp that the fan's low speed kicks on. I hated this because my fan would then always run so I had them put it back to stock temps.