Low side AC port

GTP1997

MEMBER
PONTIAC GRAND PRIX

The a/c requires recharging every year with 134a. This year when I went to recharge I hooked up to the low side and check the pressure first. It was bottomed out in the green. I turned the a/c on max and began charging until it reached the blue. It took nearly the entire can.

The a/c is still no cooler (except out of one vent which is slightly cooler). The compressor is engaging and appears to be working. The pressure gauge still shows blue when the a/c is running, but up in the red when I shut the a/c off.

Another new system which occurred only after I recharged is the blower will only operate on "5". When on 1 - 4 the blower doesn't work and air does not come out of the vents. Maybe it is completely unrelated.

Any suggestions?

7 Replies

BOOTDOG

MECHANIC
665 POSTS

If you have to charge the ac every year then you really need to get the leak fixed, take it to a shop and have them diagnose it to find the leak and what needs to be replaced. If you don't the leak will get worse every year. As of the blower problem, that would be the resistor, replace it and all the fan speeds will work.

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Friday, May 18th, 2007 AT 3:37 PM

POIDOG77

MEMBER
1 POST
1993 PONTIAC GRAND PRIX
6 CYL
54,000 MILES

Where is the low pressure A/C side?

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Thursday, June 20th, 2019 AT 4:55 PM (Merged)

FACTORYJACK

MECHANIC
4,159 POSTS

Just follow the large ac line from the firewall to the compressor It will be somewhere on there.

Here is a video and guide to help you

https://youtu.be/ON2dYcmXIAw

and

https://www.2carpros.com/articles/air-conditioner-how-to-add-freon

The low pressure charging valve is located either on the accumulator or low pressure line.

Closest I can come up with is a 92 W body Oldsmobile cutlass supreme. It doesn't differentiate 3.1 or 3.4. The accumulator is in the lower left front. The low side fitting is shown on the low side line from the accumulator to the evaporator, and the high side fitting is shown close to it. I would say if it is not in that line, it is in the accumulator, or the suction(low side) line at the back of the compressor. If there is a low pressure cycling switch on the accumulator, you may be able to remove it and use that port, just jumper the electrical terminals to close the circuit for compressor operation

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Thursday, June 20th, 2019 AT 4:55 PM (Merged)

TRACEYNUNNER

MEMBER
1 POST
1996 PONTIAC GRAND PRIX
6 CYL
FWD
AUTOMATIC
150,000 MILES

I have a problem. My car air conditioning goes off, the fan goes off also, when I am driving uphill. It only happens when I'm going uphill and also around a real sharp curve ; ie. An exit ramp curve. What is the problem with my car and what service do I need you to do?

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Thursday, June 20th, 2019 AT 4:55 PM (Merged)

EDWARD.S

MECHANIC
166 POSTS

Hi, The Way I'd Check This One Make Sure Car Is Not Low On Freon First. If That Was ok I"d Check The Pressure Switches, If they Were Ok, I'd Check The Wiring To The Ac Compressor and Fans. On Some GM Models The Wiring To The Ac Compressor Goes Under The Radiator Support. It Can Get Damaged Over Time From Parking To Close To The concrete Barriers In the Parking Lot Causing And Bad Connection At Times. And Finally Was car Ever In A Front End Collision? Could Have Wiring Problems? Without Seeing The Car, Would Be A Guess.

Hopes This Helps You,
Good Luck

Edward S.