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Old 07-18-2004, 05:19 PM   #1
2wheelride
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94 Ford T-Bird A/C problem

Friday coming home from work I had no AC 97 degrees yuck.
Saturday I noticed the A/C compressor was engaging and disengaging about every 3-5 seconds. Would a faulty relay or switch or something along those lines be a good place to start or is more info needed? Its R134 and I do have gauges to hook up and look at pressure if need be.
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Old 07-19-2004, 04:03 AM   #2
tbaxleyjr
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First, I would make sure there is enough refrigerant. Alsio make sure your manifold gages has the adaptors for a 134a system.
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Old 07-19-2004, 03:43 PM   #3
cmeseadoin
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Quote:
Originally Posted by tbaxleyjr
First, I would make sure there is enough refrigerant. Alsio make sure your manifold gages has the adaptors for a 134a system.

A compressor cycling that often first off tells me that you probably have lost your refrigerant charge. The compresor will engage and the low pressure switch says "hey wait, I haven't got any/enough pressure in my lines, turn me off before I burn up!!" Think about it methodically........you have a compressor that is getting power to the electromagnetic coil pack causing engagment of the clutch. Then you have some entity causing disengagment. What would do that rhythmically every 3-5 seconds? If the low pressure switch was bad, it would not engage the compressor at all most likely. But rapid cycling, I bet you a dollar to a doughnut that you have blown a leak and have little/no r134-a in the system. Check it out and let us know. Hook up your gauges to the high and low service ports with engine off and read the static pressure and see if you have anything. With a 3-5 second compressor running, you wont be able to get a "system operational" reading. You will have to go by static pressure with compressor off.

This is the most likely scenario. Also a refrigerant OVERCHARGE condition migth cause this too but HIGHLY unlikely and you did not say anyone serviced th system recently. Most switches are either on or off....they are not a "ok I am close-circuited, oh wait, open circuit me, ok close me, ok open me" kinds of switches that would cause cycling so rapid of the compressor. It just depends on the type of a/c system in that car and how it is electrically wired up. I "think" ford used the CCOT system but I am not sure that is the system in that car. I would have to look more into it. DEFINITLY check the refrigerant pressures. Hope that helps.
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Old 07-21-2004, 04:43 AM   #4
2wheelride
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I will do static checks tomorrow (wed) when I get home from work..... I had only checked with the motor running and well it was fluctuating with the compressor coming on and off......i havent had time to do anything since the last post ...the car was broken into 2 nights ago and well a bit of bad luck this past week ....... A/C stops working then broken window...........hopefully it is as simple as now 134 and if so then I will be looking for a leak i suppose...........thank you for the ideas and concepts

i will let you know the results of the checks

John
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Old 07-21-2004, 02:17 PM   #5
cmeseadoin
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Quote:
Originally Posted by 2wheelride
I will do static checks tomorrow (wed) when I get home from work..... I had only checked with the motor running and well it was fluctuating with the compressor coming on and off......i havent had time to do anything since the last post ...the car was broken into 2 nights ago and well a bit of bad luck this past week ....... A/C stops working then broken window...........hopefully it is as simple as now 134 and if so then I will be looking for a leak i suppose...........thank you for the ideas and concepts

i will let you know the results of the checks

John

UGH, that sucks......sorry to hear......hope you get a new window and get the a/c working.....let us know what you find. Yes, if the refrigerant is gone, definitly look for a sizable leak if it happened that fast. Evaporators are VERY leak prone because they are the weakest link. Check all lines first and look for oil. Let us know.
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Old 07-22-2004, 11:23 PM   #6
2wheelride
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The static check showed 110 PSI on low and High side. Is this what it should read? The only reading I took today was with the engine off. I think I have heard they are supposed to be balanced like that when everything is off. Thank you everyone for the help thus far

John
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Old 08-13-2004, 11:37 AM   #7
2wheelride
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i have the window fixed now and the AC appears to be working after a charge...........34 ounces i put in and it called for 32.......it seems to be holding up.......been 3 days since I put in the 134................there was no visible evidence of a leak in the first place but the system was empty....unless of course the leak happened under the dash.........anyway thanks for the help and ideas.............
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Old 08-21-2004, 05:23 PM   #8
2wheelride
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and it still is working
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