Well THAT didn’t work...

After doing a new liquid line and orifice valve my a/c still didn’t work right. The high pressure side would spike and suck down the low pressure to 20 psi where the low switch would shut the compressor off. Once the low side rises back to 50 psi the compressor kicks back on and the cycle starts all over again. So after posting here the general consensus was the accumulator was clogged. Well I installed a new accumulator and flushed the evap out. After placing the system under vacuum on the pump for an hour and then letting it sit for another hour I charged the system. The problem still remains. Cycling on and off. Now what?

you still have a restriction in it. you need to open lines again and flush out the condensing coil as well as the evap coil along with all the lines for the system.

Did you check the orifice tube? It's in the "peanut" shaped line attached to the condenser. It's not uncommon for it to become clogged but it means dirt has somehow entered the system or the compressor is failing and filling the system with shrapnel.

Orifice was changed. The thing that gets me is where did this clog come from? I’ve owned this car for 11 years and never had a problem with the a/c. Suddenly this pops up. I can understand if the compressor shit the bed but it works fine

You are not either providing enough info, or may have not filled the requisite Freon. How much did you use?

So far, your description basically sounds like it’s low on R34.

What are your gauges saying for low and high side? What is the static pressure of your low side when vehicle is off?

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With static pressure it get about 1 psi to 1 deg outside temp. When I did this it was 85* out and I had about 83psi high and low sides. When running the high side goes to about 250 and the low side drops to 20psi and the compressor cuts off. The low side pressure then rises to 50psi and the high side drops to 200 and the compressor kicks back on. This on/off cycle happens every 10-15 seconds. After I vacuumed the system I filled it with 34oz of Freon as per the manual

What happens @ 2k rpm? Cycling at idle is expected...

At anything higher than idle it just cycles a little faster

Try a new pressure switch????

Needs a new compressor.

Bad compressors don't typically pull the low side down to 20. A restriction somewhere makes sense imo, assuming charge is correct.

Sounds like a restriction in the line to me. Since high side pressure seems normal. Think about it this way, since the low side is pulling down to 20 psi, and the pressure switch is cutting out, you’re not moving enough refrigerant thru the evaporator by the sounds of things.


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How quickly does the system balance out when you shut the air conditioning off? Leave your gauge set on so you can monitor. It should balance out fairly quickly. If it does not, then you for sure have a restriction in the system. If it does the you could have a very dirty evaporator as well causing this issue.

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The system takes about 5 min to fully balance out. When I changed the orifice and accumulator I used a a/c flush on the evaporator (reverse flow) and then after letting it sit for a few minutes I used compressed air (also reverse flow) to blow everything out. It didn’t seem like there was any back pressure in there. The air and a/c flush came out real easy

Mine clicks on for about 1 second, and then clicks off again. Id like to figure it out also.

toomanytoys said:

The system takes about 5 min to fully balance out. When I changed the orifice and accumulator I used a a/c flush on the evaporator (reverse flow) and then after letting it sit for a few minutes I used compressed air (also reverse flow) to blow everything out. It didn’t seem like there was any back pressure in there. The air and a/c flush came out real easy

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That seems too long. Once the engine is off, the pressures should balance out fairly quick on a fixed orifice system.


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I would pull the orifice again to see if it caught anything.


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98 svt said:

Mine clicks on for about 1 second, and then clicks off again. Id like to figure it out also.

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Most common cause of that is when they're low on refrigerant.

olympic said:

Most common cause of that is when they're low on refrigerant.

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I tried filling it but it pissed back out the valve.

98 svt said:

I tried filling it but it pissed back out the valve.

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Pissed back out what valve?


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