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I've already gone thru the troublshooting flow chart and replaced a defective cycling switch,now the clutch cycles every 15 seconds or so. Can someone point me in the right direction for my next move? Thanks in advance.
 

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First thing I'd do is check pressure on the low and high side. It may be low on refrigerant. I'm assuming you have an R134a system (94+)?

The only way to be sure the charge level is correct is to use a gauge set that shows high and low side pressures. The low side will be between ~25 and 40 PSI to maintain cold but above-freezing temperatures. The high side is the indicator of overall system charge level. Use the chart below for the acceptable ranges, relative to ambient temps, to determine if you are in fact low on refrigerant:

If the readings are off or don't seem right, there are other possibilities (e.g. a clogged orifice tube).
 

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Sounds low on Freon. When my 97 was low it drove me crazy - the car constantly bogging every time the clutch kicked on. Going up a hill at low speeds was not fun.

You'll have to take it to a shop to have them diagnose it unless you have all the equipment.

Al
 

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Sounds low on Freon. When my 97 was low it drove me crazy - the car constantly bogging every time the clutch kicked on. Going up a hill at low speeds was not fun.
Couple things with that statement I want to point out (will I get in trouble if I do? :tongue:)... first (being nitpicky), Freon is the DuPont trademark for R12. R134a has no brand or trademarked name. Second... if your car bogged down every time the clutch cycled, there was something else going on with it. Yeah, you'll notice when the clutch cycles if you're in tune with the car (vibrations, feel, power levels)... but if it was bogging down every time the clutch engaged there was something else wrong with it. Even when my old 3.8 Cougar was low on refrigerant it could negotiate hills at 35 or 36 MPH in 4th gear with the clutch cycling.
 

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If it's bogging the engine, I'd listen for the belt to start squeaking; if it does, the compressor is toast.

If the compressor stalls, it either slips the belt or kills the engine.

I have the "stuck compressor problem" on the tbird.

I pulled the pressure switch connector off so I can run the defrost.
 

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The first time I hit the defrost in the Tbird, the front belt started smoking and squealing; scared the crap out of me, lol.

I opened the hood and unplugged the pressure sensor, no more problem, lol.

I needed defrost bad. :)
 

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Funnily enough, the previous owner of the car (weird to say, now having owned it for 15 years) hotwired the system so the compressor would always be engaged. He disconnected the cycling switch and stuck a paper clip into the connector - probably because it was low on refrigerant (and oil!). So on that trip home... I had the defrost going and after an hour of running with insufficient oil it must have just... overheated and seized up. I can say though, rebuilding the system after that was a great learning experience - haven't had to touch the system in any way since I did that. Wow, that was like 10 years ago. :)
 

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The Tbird is a 97, so the system is completely different than the 96's, and not available.

I'm seriously considered putting the compressor I took off the Red Cougar on it, but I'm sure the system is full of garbage.

I'll eventually rebuild it, but not soon. Tennessee isn't hot enough to absolutely have to have AC. :)
 

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Yah, a full rebuild and they're ice cold.

That's one of the things that pissed me off about the motor dying in Ruby; to redo it, I get to drain the system and rebuild it. Again.

RwP
 

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... if your car bogged down every time the clutch cycled, there was something else going on with it.
I was merely pointing out that the small drag you get when the A/C kicks on at low speeds climbing a hill (and you know what I'm talking about), was far more noticeable when it cycled constantly from being low on R134a. I know its slow around here and all but jeez......

Al
 

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I usually bring my cars to either of the two a/c shops near where I live that I trust. But when my 95 was doing that (cycling too frequently) and not cooling good enough a couple months ago I added a can of refrigerant that I had on hand, works fine now. You sound like a DIY type of person, so investing in pressure testing equipment to assist with the diagnostics is your best long term solution.
 

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Discussion Starter #14
Thanks,Jim. My only manifold gauge set is for R-12,so I looked for a set of fitting adapters,but they cost more than a whole new R134a setup.
 
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