6.0 A/C Problem - Ford Powerstroke Diesel Forum
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post #1 of 5 Old 05-22-2012, 07:59 AM Thread Starter
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6.0 A/C Problem

My A/C has been getting warmer over the past month or and now it is just blowing warm air so so I decided to get a bottle of 134-R and charge the system. I went to Advance Auto and picked up the best one they had, its a pro series bottle with trigger and gauge and stainless steel braided hose.

I followed the directions on the can, turned on the truck put it on MAX A/C and hooked up the hose to the low pressure side port on the truck, pressure read at 0. I pulled the trigger until the pressure read in the green area (about 40psi) and then I heard the compressor click and the pressure dropped to about 15psi and then crept back up to about 40psi, then the compressor clicked again and the pressure dropped back down to about 15psi.

Does this sound like I need to add more freon or is their something else wrong? I've not to familiar with A/C work and have never had any problems with A/C before.

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post #2 of 5 Old 05-22-2012, 08:31 AM
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Doesn't sound like your A/C is staying on while your filling it. The compressor needs to be constantly running while pulling the trigger on the can this will give you the most accurate reading. My a/c was intermittantantly going to warm and never getting real cold did the freon etc could never get it into the green range. I checked under the hood and found a small vacuum line that runs from the vac pump to what I think is the heater control valve and it fixed the issue. Good luck!

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post #3 of 5 Old 05-22-2012, 08:45 AM
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You really should get a gauge set and read the high and low side pressures to know what is really going on. With that said, the low side has a pressure sensor that shuts off the pump when it gets lower then about 25 to 27 psi. That is why your pump is cutting in and out; the low side pressure is too low.

Most likely you will need to add more so that the low side pressure stays a little higher and the pump runs all the time (or at least most of the time). You should also monitor the high side when you do this so the high side pressure doesn't get too high. If the high side pressure gets too high it will destroy the pump.

If you don't have the money to get a gauge set, or have a professional work on it, and want to risk blowing the pump out add just enough to keep the low side pressure around 25-30 psi while the engine is running at 1,200 to 1,500 rpm.

I am not an AC professional, but I have worked on a few fords.
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post #4 of 5 Old 05-23-2012, 06:31 AM Thread Starter
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Thanks for the advice guys. I'll get some gauges and see what they read out. Hopefully I'm just low on freon.

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post #5 of 5 Old 05-23-2012, 12:40 PM
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Mine did the same thing. Worked great for a few months after I bought it then over a week or 2 it got warmer and warmer. I tired adding freon lik eyou did and it seemed to work at first but the next day it was hot again. The A/C compressor kept cycling though like it was working. (the ambient temps were mid 50's at night and mid 80's day time) I had the cheapy guage from the refill can on the low side (blue cap) and it was fluctuating like yours. I borrowed a set of guages from my buddy and the high side was pegging out right as the compressor kicked off.

I took it to a local shop and they checked the system. They found "sand" in the system and a plugged orrifice tube. They wanted to replace the entire system for $2200. There is a Technical Service Bulletin (TSB) from Ford related to the problem. (the link is below summarizing the bulletin.

A/C doesn't seem very cold

I flushed my system myself and replaced the acumulator/dryer for $50 and had it recharged at a reliable shop for $150 and it works better than when I bought the truck.

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