What is wrong

R

RedStang88

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Aug 14, 2003

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#1

• Aug 30, 2004

• #1

When I turn on m a/c, it is cold but then it gets hot. The temperature gauge fluctuates with the a/c, the gauge reads between the m and the a on normal when it is hot, and then the gauge goes back between o and r when the a/c is cold. I am worried that my car is overheating but dont know if I can trust the gauge. What do you guys think it could be?

 

HISSIN50

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#2

• Aug 30, 2004

• #2

yes. get a real gauge. for reference, the puter kills your a/c at ~226* and under WOT, per the TPS (on most cars, the a/c will shut off via the WOT relay with much more than 2/3 throttle. remember it is via the TPS, not absolute pedal travel).

good luck.

 

giddyup306

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Oct 22, 2002

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#3

• Aug 30, 2004

• #3

Sounds like a bad pressure cycling switch. Hard telling though not seeing the car and all.

 

R

RedStang88

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#4

• Aug 30, 2004

• #4

So if the gauge is f'd up, the computer will think the car is runnin hot and shut off my a/c? Or if I push the pedal too far? Also, I have an amp runnin my 6x9s, when I brake the volume seems to go lower. All these problems started at the same time, do you think there is a problem with a ground somewhere. I noticed when the gauge reads between the o and the r, the a/c is ice cold, and the stereo is really loud.

 

HISSIN50

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#5

• Aug 30, 2004

• #5

giddyup, nice point. RS88, when the a/c gets hot, do you know if the a/c compressor has disengaged? if not, the LPS and WOT relay are ok.

the guage has its own one wire sending unit. the puter gets its temp values from a different sensor.
i would really suggest getting a real gauge (ditto for oil pressure). then you can diagnose stuff a little more.

good luck.

 

R

RedStang88

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#6

• Aug 30, 2004

• #6

Im pretty sure the compressor is kicking on and off, because it sounds like it when the car is idling. I never popped the hood when this is happening. My temp gauge moves around alot thought with the a/c off. Do you think the car is overheating?

 

Gearbanger 101

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#7

• Aug 30, 2004

• #7

Sounds to me like your orifice tube is plugged. Why do I know, cause I just finished fixing the exact same problem with mine. Blows cold at first, then the pressure builds up because the coolant isn’t circulating it’s way back to the compressor and it shuts down. $47.00CAN for a new line and a large double, double to have my buddy charge it and I was back in business.

 

R

RedStang88

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#8

• Aug 30, 2004

• #8

Where is this orifice tube at, and it will cause my car to heat up? If I dont use the a/c will the car run colder? I noticed on the highway everything runs great.

 

jrichker

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#9

• Aug 30, 2004

• #9

RedStang88 said:

Where is this orifice tube at, and it will cause my car to heat up? If I dont use the a/c will the car run colder? I noticed on the highway everything runs great.

Click to expand...

The orfice tube is INSIDE the high pressure supply line for the evaporator. Unless you have some tools & A/C service experience, it is not a job you would want to undertake. You would need to remove/recover all the refrigerant in the system, disconnect the high pressure supply line from the evaporator. Then you get to try and fish it out with some needle nose pliers or other tool. The system gets vacuumed down and then recharged with refrigerant.

 

Gearbanger 101

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#10

• Aug 30, 2004

• #10

jrichker said:

Then you get to try and fish it out with some needle nose pliers or other tool. The system gets vacuumed down and then recharged with refrigerant.

Click to expand...

Actually....fishing it out is impossible. The tube is actually crimped into the line, which takes a 90* bend at one end, and travels about 16-inches at the other before taking another 90* bend. The tube itself was only about $3.00 (which I bought the first time around) but it's the same one used in a lot of Ford cars, which is why it can be bought separately. But you literally have to replace the whole line on a Mustang. Which actually isn't that tough, assuming you've got the proper disconnect tools pictured below and someone to recharge the system for you afterwards.

 

J

Js5ohLX

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#11

• Aug 30, 2004

• #11

Ok, before you go changing parts, your problem is going to be heat. When the condensor is hot, you have higher pressures, the temperature of the condensor actually just about equals the high side line pressure. So you're building too much pressure, and that's why it's kicking it off. Try blowing out your radiator and condensor to allow more airflow, most cars are pretty plugged up, make sure your fan is working well. If it's not electric, test your clutch, if it is electric, make sure it is sufficient. The cooler you get the condensor, the cooler your air will be inside the car. I know this because I'm ASE in A/C.