A/C Cuts off on very slight acceleration

[SableSal]

Hey guys, just thought I would pick your brains about an A/C concern I have. I recently replaced the compressor on my 95 GT due to a bad clutch coil. The clutch wouldn't engage when power was applied to it. Anyhow, I figured I would replace the compressor as well. I just don't know how old the compressor was. Anyhow, I replace it and the o-rings that go with it. I also replaced the o-rings on the high side hose, since it felt a little loose (figured it was a bad seal). Anyhow, I vacuumed the system as best as I could (one hour at 40PSI on a Harbor Freight vacuum). I then began to charge the system. My gauges were ****, and I couldn't really get a good reading... I said forget it, and took it to work with me (I work for a Toyota Dealer). I then set it up on the A/C machine and was about to evac the system and recharge it. I evacuated 1.42lbs of freon. Looks like I was almost there. I then charged it with the recommended 2.1lbs of freon. The A/C was blowing pretty cold. I got it down to 52 degrees at idle. When I would drive, it would get colder (it felt like 40 degrees. Anyhow, now I notice when I am coming to a stop, or in stop and go traffic, the A/C isn't as cold. Sometimes it'll get pretty "vent" like air coming from it. I do notice, if I'm driving at highway speeds or cruise at a constant speed, the A/C is blowing pretty cold. I was thinking it was low on freon and I have a leak somewhere. But, it's filled 100%. I was starting to think the UDPs I have on the stang are under driving the A/C compressor. I've recently replaced the Low Pressure Switch as well with a new one. I also have a Mishimoto Radiator. Engine temps have always been around 212 and have gotten up to 220 on a hot summer day. I'm wondering if the T-Stat isn't getting stuck. A hot motor could get the A/C to start cutting out... I'm kinda stumped at this point. Any tips would be greatful!

 

[toyman]

Hey guys, just thought I would pick your brains about an A/C concern I have. I recently replaced the compressor on my 95 GT due to a bad clutch coil. The clutch wouldn't engage when power was applied to it. Anyhow, I figured I would replace the compressor as well. I just don't know how old the compressor was. Anyhow, I replace it and the o-rings that go with it. I also replaced the o-rings on the high side hose, since it felt a little loose (figured it was a bad seal). Anyhow, I vacuumed the system as best as I could (one hour at 40PSI on a Harbor Freight vacuum). I then began to charge the system. My gauges were ****, and I couldn't really get a good reading... I said forget it, and took it to work with me (I work for a Toyota Dealer). I then set it up on the A/C machine and was about to evac the system and recharge it. I evacuated 1.42lbs of freon. Looks like I was almost there. I then charged it with the recommended 2.1lbs of freon. The A/C was blowing pretty cold. I got it down to 52 degrees at idle. When I would drive, it would get colder (it felt like 40 degrees. Anyhow, now I notice when I am coming to a stop, or in stop and go traffic, the A/C isn't as cold. Sometimes it'll get pretty "vent" like air coming from it. I do notice, if I'm driving at highway speeds or cruise at a constant speed, the A/C is blowing pretty cold. I was thinking it was low on freon and I have a leak somewhere. But, it's filled 100%. I was starting to think the UDPs I have on the stang are under driving the A/C compressor. I've recently replaced the Low Pressure Switch as well with a new one. I also have a Mishimoto Radiator. Engine temps have always been around 212 and have gotten up to 220 on a hot summer day. I'm wondering if the T-Stat isn't getting stuck. A hot motor could get the A/C to start cutting out... I'm kinda stumped at this point. Any tips would be greatful!

Not certain what the question is. The rad fan should be on high at idle and to about 45 mph. The throttle A/C off occurs at about 70% throttle open. Cooling is about 40*-50* below ambient temperature.

 

[SableSal]

Just wondering what would cut off the A/C. I'm going to replace the A/C relay. Tighten the connectors at the A/C Compressor and Low Side Pressure Switch. I'll let you know how that goes.

 

[SableSal]

Ok, so I checked all the connections. Nice and tight. I turned on the AC and noticed the clutch engaged about 5 mins after I turned on the A/C. Which is good... Although it never disengaged. I waited for about 2 mins or so. I then went WOT and it disengaged as I suspected it would.

Could this be an air gap problem? Is this normal? Could there be barely enough freon in the system to keep the compressor on, but not disengage the clutch? I guess best bet is to check it with gauges and see what's really going on... Any input would be great.

BTW Air vents seems pretty cold when I checked it. I'll turn it on while driving home and see what happens! KABOOM! lol

 

[SableSal]

Could this be an air gap problem? Is this normal? Could there be barely enough freon in the system to keep the compressor on, but not disengage the clutch? I guess best bet is to check it with gauges and see what's really going on... Any input would be great.

Anyone?

 

[HISSIN50]

How did you pull 40"?

Since it blows cool at higher RPM (while on the highway), you should have enough refrigerant in the system.

I like the idea about low compressor speed, possibly low alternator output and fan speed. If you hold it at like 1000 or 1200 RPM, is it better?

You can check your clutch gap easily if you want. It's probably fine.

You're not hot enough to be having the EEC shut off the AC because of temps.

 

[SableSal]

How did you pull 40"?

Since it blows cool at higher RPM (while on the highway), you should have enough refrigerant in the system.

I like the idea about low compressor speed, possibly low alternator output and fan speed. If you hold it at like 1000 or 1200 RPM, is it better?

You can check your clutch gap easily if you want. It's probably fine.

You're not hot enough to be having the EEC shut off the AC because of temps.

HISSIN50, Thanks. I think I have an freon leak coming from the liquid line. I also kinda did this quickly and installed a compressor and didn't replace the Accumulator. Also, after attempting to recharge the system at home, I found the low side service port leaking like crazy. I changed it out, and then the high side was leaking. I changed that one out too. I'm sure that accumulator is toast. I bought both for $46 new from NAPA (I have a friend that hooks it up!). I'll evac it all out and see how many pounds I pull. I should be low. Then I'll install the liquid line and accumulator, I also plan on replacing all the o-rings on all the lines. NAPA sells a o-ring kit specifically for our cars that has all the sizes needed. I'll then vacuum the system and recharge it all over again!

I'm also planning on installing the stock pulleys too. I definitely think that fan speed and compressor speeds are not helping. Also, getting the water pump back to speed should help in the horrid 105* summer too!

I'll keep you guys posted. This should help me tons!