Air Conditioning Compressor not staying engaged? (VIDEO ATTACHED)

[Bigscrb15]

My a/c has never been very cold and usually takes quite awhile before getting cold. After this winter I haven't had a/c. It blows warm. I figured it was low on refrigerant so I bought a large bottle. I hooked it up and the guage shows it building pressure and then dropping off over and over. Here is a video. Is this a problem with the compressor? I have hear it will do that when low on refrigerant but I don't want to add more and over pressurize the system and cause damage. Any ideas? It is hard to see in the video but it builds up to about 50psi before dropping. Ambient temp is about 70*.

Here is the video

[Banshee365]

Is the clutch clicking on and off when it's doing that? It's hard to hear in that video. If you're A/C isn't blowing cold it may just need to be recharged. I have never been a big fan of the DIY gauges they sell at auto parts stores now. I feel to properly fill a system you need both low and high side gauges.

Keep in mind that the system is designed to cycle. There is a pressure cycling switch on the system that tells the cluth on the compressor when to engage and when to disengage. This is due to the design using the orifice tube instead of an expansion valve. The systems with expansion valves will keep the clutch engaged and regulate the pressure with the valve. Ford's systems use a $5 plastic plug in a line with a tiny little hold in it to expand the refrigerant. This cannot regulate the pressure so the compressor must cycle. If you have a friend with a shop or something maybe have them charge it up and go from there.

Now does your A/C blow warmer than it is outside? If so you may look into a vacuum issue to the heater valve. Maybe unplug the vac hose on the valve and make sure it's closed to make sure you're not getting heat over your cold air.

[Bigscrb15]

Yes, the clutch is kicking on and off. The air does blow pretty warm.... Do you know where the valve is you were talking about?

[Bigscrb15]

I found the valve. I am going to play around with it tomorrow once it is warm outside.

[Bigscrb15]

Well... I have kinda just accepted the fact my ac didnt work and havent worked on it much. After repairing my FICM I am thinking I am Mr. Goodwrench now. I don't think I actually found the heater valve. The air blowing out is a good 10-20 degrees warmer than the outside ambient temperature..... Anyone know where this valve is and how to bypass it to test?

[dannyboy950]

It is located by the pass.side valve cover inline with one of the heater hoses.
There is a grey plastic vacum line that plugs into the silver looking canister. The line does not fit well and is prone to comeing off. When you switch to A/C vacum closes the valve cutting of hot water to the heater so your a/c can work

[Bigscrb15]

Thanks... That is the same valve I found last time and messed with. Do you know if I need suction to close or open the valve? Trying to figure out how I can test this theory....

[Bigscrb15]

The valve seems to be operating fine. I tried it both opened and closed and I still got warm air blowing. I am back to thinking that my refrigerant may be low. As you see in the video I was using a cheap DIY kit to test the pressure. I will try to get it tested with hi/low guages today.

[symbols]

I can't see the vid.....

[Bigscrb15]

Originally Posted by symbols

I can't see the vid.....

qik only hosts the video for so long. my first post was back in march. i don't have access to the video sorry. It just showed the $20 guage and can of R134a from autozone hooked up to the truck and the compressor was cycling every 5-10 seconds. The pressure would build up to the "danger zone" lol....