converted A/C not working in my 1992 XLT

[Roeseph]

Hello, I recently aquired a 1992 XLT from a family member. I'm trying to repair all the things that were ignored before I took over ownership, and I'm not sure what is wrong with the air conditioner. Before I ask my question, let me give you a little backround history on the A/C system. Last spring, The A/C was blowing hot air, the compressor continued to run, it just didn't get cold. The truck was taken to a shop and converted to r134A in March. The air worked all summer just fine. Now it's a year later, and when I turn the A/C on, the compressor kicks on for about 5 seconds, then stops. after about 10 seconds, it kicks on again, then stops. Over and over. And thats about all it does. According to the paperwork, this is what the repair shop did:
1. suction and discharge
2. remove and replace manifold and tube assembly
3. remove and replace drier and accumulator
4. add refrigerant 134a
5. a/c system dye
6. a/c retrofit kit

I read in another thread that the compressor cycling like that would be an indicator of low refrigerant level. I'm just not sure that applies here because before the conversion, the compressor would run regardless of whether or not there was enough refrigerant in the system. I don't want to add refrigerant if that's not the problem, and mess it up. Would that apply here?

Any insight or information would be highly appreciated. thanks!

Also, if it is in fact a refrigerant leak, is there an easy fix that won't involve me having to completely tear down the A/C system? I can work on my own vehicle, but I've never dealt with an A/C system before, and I don't understand how it all works. Thanks again!

Matt - Illinois

 

[Gatorblazer]

Remember to search, but I think I can help. If its low on 134, you can check it yourself. Go to a local HVAC store, maybe even OReily's and try to find a set of gauges to read freon pressure. They are anywhere from twenty to $120. JC Whitney has them to. Get a can of 134 from a autoparts store, and make sure to get the charging nipple. You will need a different connection for your gauge hose to charge/read the system. This may or may not come with the 134 can. Hook the blue hose with the charging nipple on the low pressure side of the system. If its low, it will read between 0 and 5. If low, charge the system with 134. Not sure about 134, but on a 12 system, the low side should read around 25psi. Just a little advice, if the 134 lasts you all summer, then I would just fill the system up each year rather than replace the compressor. They can get expensive. Welcome to the site!

 

[sprint29]

Roeseph,
I used to work for a company that had a fleet of trucks that I retrofitted to 134a, and I`ve done probably 125 to 150 of them. I did all of the a/c work, so I would see the truck anytime it needed a/c work.
After doing maybe 20 or 25 I started seeing the same trucks back being low on freon, so I did some checking. I found that the Schrader valves on the conversion adaptors weren`t all tight. After that I reduced the number of comebacks, for being low, about 98%.
Check and see if they are tight on your truck. It`s just like the tire valves on your wheels, except 134a systems use a large sized Schrader valve and you need the appropriate tool. It should be available most anywhere, (eg. Auto zone ect.) for a few bucks. Just stick the tool in carefully, and make sure the tool sits down on the Schrader valve properly and tighten it a little. Don`t loosen it, as some freon could leak out.
By the way, I`m talking about the adaptors that screw on where you hook up the gauges. I just don`t know how much you know, (no offence) and an a/c system can be dangerous if you aren`t sure of what you`re doing.

 

[Brock94]

The service valves are a common leak point, even when new-- I fixed mine with a new plastic cap that has a good rubber seal in it-- make sure yours is on tight. People don't realize how important that plastic cap is to getting a good seal.

Also, before you go and recharge the system make sure it's really low. The compressor clutch will cycle off if the ambient temperature (outside air temperature) is cool or cold. This is a safety function that prevents the system from getting damaged. I don't know what the weather has been like in Illinois, but maybe it isn't warm enough for the system to operate continuously yet. If that's the case, wait until it's at least 70 out and see if you get cold air at the vents-- if you get cold air at the vents the system is working properly, if it's still cycling the way you describe, then it is likely that the charge is low.


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[BrooklynBay]

You could check the valves with a little Windex, or some sort of bubble solution. Hercules makes a leak detector liquid that is available in the plumbing stores. It is used on gas line fittings.

 

[Roeseph]

Thanks for the advice, everyone. I went to the auto parts store, and found a can of r134a that included lube and "leak stopper". It also had a gauge built into it. When I connected the can/gauge to the service valve, it read that I had way too much pressure. Then when the the clutch kicked in, the gauge went down all the way to the "low" mark, then the clutch kicked out, and it went back up. So, I waited till the clutch kicked in again, and started adding refrigerant until it stopped again. after a couple cycles of doing this, the compressor started running much longer between cycles, and the level on the meter was dropping to the "normal" mark. at this point I unhooked the can, put the cap back on the service valve and went for a drive. Though the compressor still cycled on and off, it ran for a much longer intervals, and the air was definately working. We'll see how long it lasts. thanks again!

Matt - Illinois

 

[Gatorblazer]

Pressure will be higher when compressor is not on. That is normal. Pressure will not be accurate until it is working (on). Glad you got it working, and welcome to the site.