A/C Will Not Blow Cold

Tiny
MSTRAWDER
  • MEMBER
  • 1994 MERCURY COUGAR
  • 86,496 MILES
Bought this car used and I'm having the above issue with the a/c. When I turn the system on, the compressor will cycle on and off at approximately a 5-6 second interval. I assumed it was low on freon and bought a recharge kit at the parts store. It reads around 50psi with the system on max connected to the low-side port. The line going into the firewall is nice and cold, but the air blowing inside the cabin is warm. If I turn the thermostat over to heat, it blows very hot, so I believe the blend door is working properly. Even if I short the pressure switch to cause the compressor to stay engaged, the line will ice up, but still only warm air inside the cabin.
Monday, April 9th, 2012 AT 11:42 PM

6 Replies

Tiny
DJCL
  • MECHANIC
  • 767 POSTS
Your blend door may be working but not closing all the way. Also 50 psi on the low side is to high. Should be more like 35 psi. Do you have a hi side reading.
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Tuesday, April 10th, 2012 AT 12:10 AM
Tiny
MSTRAWDER
  • MEMBER
  • 24 POSTS
No I don't unfortunately. The kit only came with a low side gauge. If the low side is showing that high of pressure, would the compressor still cycle like that?
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Tuesday, April 10th, 2012 AT 1:03 AM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Possibility here-could be overcharged, moisture in the system and compressor problem-
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Tuesday, April 10th, 2012 AT 2:06 AM
Tiny
DJCL
  • MECHANIC
  • 767 POSTS
Have the system evacuated see if it holds vacuum and a proper recharge. Start with that. This is somthing you will have to have a shop do. Let me know how it works out.
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Tuesday, April 10th, 2012 AT 6:40 AM
Tiny
MSTRAWDER
  • MEMBER
  • 24 POSTS
I have not had the opportunity to take the car to a shop yet, but a suggestion was made that I would like to know if it is really a possibility before I waste time and money. As I stated, the line going into the firewall is nice and cold, but the return line coming from the firewall is not. I was told this is correct. However the line coming from the accumulator I'm told is where the orifice tube is and that if it were plugged, the freon would not continue it's cycle, thus causing the compressor to cycle on and off as the pressure would build up. Does this sound like an accurate possibility?
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Saturday, April 14th, 2012 AT 12:08 AM
Tiny
DJCL
  • MECHANIC
  • 767 POSTS
With out the hi side reading its a gess. To check the tube you will have to evac the system. I think on this car its called a liquid line. It might be sealed in the line. You would have to replace it and then recharge the system. Also if it is plugged then something els is going on with the system.
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Saturday, April 14th, 2012 AT 12:24 AM

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