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I recently purchased an 89 FSB 5.0 and when i turn on the A/C, the compressor kicks on and off every 3-5 sec until i turn it off. Any ideas?
 

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Low refrigerant
 

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you might have a leak , if your high and low pressure switches are working properly then i would check for low refrigerant.low pressure ac compresser turns on /high pressure ac compresser turns off .
 

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Def. check the freon level before you go buying anything. If freon level is good than buy a pressure switch...they don't cost that much.
 

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The low pressure switch cycles the compressor, to keep from damaging the compressor in a blockage situations. Your bronco could be low of freon or like mine, have a blockage in the system.
 

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I recently purchased an 89 FSB 5.0 and when i turn on the A/C, the compressor kicks on and off every 3-5 sec until i turn it off. Any ideas?
You are low on freon. There is no high side cutoff, only a low side cutoff located on the filter/drier assembly. Get a can and don't fill it past 50-55 psi with the engine running, A/C on max with dial turned all the way to cold. For like $20 or so you should be able to get a can with a pressure gague on it. While you're filling it, you should notice the time between it kicking on and off increases. Good luck!
 

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Discussion Starter #7
I bought a recharge kit and began filling the system. The pressure guage was reading pretty low 20psi? As i was filling, the compressor was clicking on and off at a slower interval. As I was almost done with the fist can, my wife called and said she was going into labor. Perfect timming. When I pulled the hose off of the connector the refrigerant started spewing out of the connector. The pressure never got above 35psi so I'm guessing that there is some kind of obstruction in the line somewhere. I havent tried to refill it since the baby came. I was thinking of taking it into the local auto shop and have them narrow down where the block is; then i can just replace the part myself. Any suggestions?
 

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orfice tube

mine was pretty clogged up and they are easy to replace
when you do you might as well replace the accumulator as well they're cheap and you can replace the two o rings for it and eliminate the most common leak points in these systems
the accumulator should run you about 30 to 50 or so and o rings are cheap to get as well
when i got mine the o rings that came with it were the wrong size so i had to buy different ones to replace them but it still doesn't cost much
when you do the accumulator you will need to drain the system completely and have it vacuumed out once every thing is put back together and if it holds vacuum then your good to charge it up
you'll need to either take it to a shop to have it vacuumed or find a buddy that has a manifold gauge set and a vacuum pump
those are not cheap so it would be best to find someone that has that stuff already
i have a friend that happened to have all of that stuff already so it made things alot easier
when you go to buy all of your parts talk to the guy behind the counter and they should be ale to fill you in on what all you'll be needing to get it done right
if you have any more questions feel free to ask
 

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I assume that recharge kit you purchased was R-134a and the truck already had to adapters on the service ports? It is never a good idea to mix R-12 and R-134a. Going on the assumption the truck was previously converted the low side pressure should never be above ~45 PSI with the compressor running. The low pressure/clutch cycling switch is designed to work in the ~23-45 PSI range. Above or below it shuts off power to the clutch. Without a manifold gauge set to look at both the high and low side pressures it is difficult to diagnose if there is a problem.
 

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Discussion Starter #10
So i went out to run the A/C for the first time since it was spewing refrigerant and the compressor didnt even kick on (i ran it for 5min). Im guessing the system is empty now. Yes, the system has already been converted and has the adapters. I guess i will look into replacing some of the cheaper components and then vaccuming the system. Thanks for the suggestions!
 

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So i went out to run the A/C for the first time since it was spewing refrigerant and the compressor didnt even kick on (i ran it for 5min). Im guessing the system is empty now. Yes, the system has already been converted and has the adapters. I guess i will look into replacing some of the cheaper components and then vaccuming the system. Thanks for the suggestions!
Your initial problem was that you were low on freon. Your problem now is that your schrader valve got stuck open or is leaking, which is why it spewed out when you took off the service hose. Now that you have no charge in the system (presumably) you can replace your orifice tube. The tool to crack the fitting is like $6 at autozone, the orifice tube is like $2. If you live in a hot climate, get a blue one. Needlenose pliers will pull the old one out, pop the new one in and you're in business. Follow the skinny line on the passenger side of the engine that goes in to your firewall. The orifice tube is located in the hard line going in to the firewall.

The problem with these systems is that there is no filter going in to the orifice tube, so it will get clogged if there is crap floating around. Autozone sells an in line filter you can put before the orifice tube that will help, they're like $16.

Do all the repair work as quickly as possible because humidity ruins the internals. I would replace any o-rings you encounter, as well as the one on the low pressure cutout switch. Replace the schrader valve core just like you would on a tire. As far as evacuating the system, you can buy a venturi box that will do it at harbor freight, they are less than 20 bucks. I didn't evac mine and I have had no problems as a result.

I also put an electric fan on the driver side behind the grill that runs any time the compressor is on (basically anytime the truck is running). This will help to keep from overheating, but will also greatly improve the efficiency of the a/c system and keep your high pressure side in check.

As far as charging the system is concerned, here is the best way to do it:

Vehicle off, hook up the 134 to the service port. Let it sit for 5-10 minutes to build pressure in the system.

Start engine, A/C on max, temp all the way to cold (compressor should be cycling on and off)

Fill the system until the accumulator is cool to the touch or even wet with condesation, regardless of how much pressure is in the low side (Don't go over 55, of course) The compressor will cycle less and less frequently, and ultimately will stop cycling all together.

If you overfill, the system will prettymuch stop working because there is no way for the liquid freon to expand. You can also damage the compressor by overfilling it. If you find this happening, bleed some pressure off until it works again.

My 92 bronco has 53ish psi on the low side after running max a/c for 5 minutes. My typical day is 110-115 degrees and it will get the truck cool after about 5 minutes. The only thing I wish I had was a more powerful fan because it seems like it has the potential to cool more, there just isn't enough air flow.
 

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Going on the assumption the truck was previously converted the low side pressure should never be above ~45 PSI with the compressor running. The low pressure/clutch cycling switch is designed to work in the ~23-45 PSI range. Above or below it shuts off power to the clutch. Without a manifold gauge set to look at both the high and low side pressures it is difficult to diagnose if there is a problem.
The switch will only cut out if it's low on pressure, it doesn't matter how high it gets, it will stay on.

As far as going over 45 psi on the low side, it really depends on the climate. The more pressure on the low side, the greater pressure potential on the high side, which will provide more cooling as long as it's not charged to the point where liquid refrigerant is leaving the accumulator.
 

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I was thinking one thing, then typed another as you pointed out. The turn on point for the clutch cycling switch is ~45 PSI. In warmer climates or when converting to R-134a it is recommended to use a red orifice tube, not the standard issue blue as factory installed in R-12 systems.
 

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Discussion Starter #14
Success!...I went to autozone and replaced blue orifice tube with red one (the one i pulled out was gunked up) $2, when ahead and replaced the accumulator because it was cheap $25, bought recharge kit with new o-rings, high and low adapters, pressure guage, and 3 cans of refrigerant. Filled system with 2 1/2 cans; sitting at 45 psi and blowing cold air. Thanks guys!
 

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:beer
 

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:beer

have a cold one
 

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Is there anyway to flush and unclog the orifice while keeping everything intact?
My compressor is cycling on and off. Two seconds on then two seconds off. It is blowing hot air and the pressure on the high side is way high. I'm assuming there is blockage.
The truck has also been sitting for about a year and a half.
 

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Is there anyway to flush and unclog the orifice while keeping everything intact?
My compressor is cycling on and off. Two seconds on then two seconds off. It is blowing hot air and the pressure on the high side is way high. I'm assuming there is blockage.
The truck has also been sitting for about a year and a half.
No, there is no way to flush the orifice without first removing the refrigerant and disconnecting the line. Even if there was, the junk that's blocking the orifice would still be in the system and would just block up something else. You need to remove the refrigerant, disconnect the line at the evaporator, remove the orifice tube (they're only like $3, so you might as well get a new one), install the new orifice tube, reconenct the line, evacuate the system and recharge.
 
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