lost the air conditioning

[Giusto]

I leave for a trip out to Colorado on the 7th and my air conditioning just petered out. It was there one day and then not. It did slowly drop out though — it wasn't all of a sudden.

I know nothing about the air conditioning in an 80. What should I look for? I wonder if I just need to charge it. Can someone point me in the right direction?

 

[bloc]

First place to look is at the pulley of the compressor.. is the center turning with the belt (ie, compressor clutch engaged)?

 

[Giusto]

Yes, the center is spinning with the belt.

 

[98 SNAKE EATER]

Can you tell if the lines are getting cold?

 

[AMX390]

Are there bubbles in the sight glass, located above the battery on the sidewall, when it is running?

 

[Giusto]

98 SNAKE EATER ... the lines are chilly. It's a cool morning here however. I let the engine run for about 10 minutes and there is definitely a chill to them.

AMX390 ... there are bubbles.

Here are a couple videos:

Bubbles:

Compressor turning:

 

[blkprj80]

Looks low on refrigerant. Mine has really fine bubbles in the sight glass, almost milky white, but no bigger bubbles. When the compressor cycles off, I see large bubbles. I'm fairly sure mine is filled properly, and it's cooling and cycling like it should.

Find a friend with gauges and have them add some refrigerant and you should probably be good for a trip, then take it to a shop who can find the leak and fix it. If you take it to a shop for just a quick fill, ask them to add UV dye so you can spot the leak later.

One likely suspect for a leak is the Schrader valve under the L and H caps. I sometimes get a bit of pressure when I remove the caps. I replaced the Schraders while I had the whole system apart.

 

[AMX390]

There should be no bubbles and you should charge at a very slow rate until it clears up. There is a reason that it is called the "liquid line" and should be free of any action. As mentioned, do a slow charge, because over filling is worse than under.

 

[Tools R Us]

What are the gauge readings, if your going to work on A/C should have access to gauges. The year of the rig is secret, but if it's R134, the amount of bubbles in the sight glass is dependent on temp, etc, mostly not accurate for charging.

 

[AMX390]

It's actually probably the best way, other than starting from scratch and weighing it in. Trust me, if your ac is all up to snuff and you do a slow charge, right to where the bubbles are gone, it will have the optimum charge, especially if you are without gauges.

 

[Tools R Us]

It's actually probably the best way, other than starting from scratch and weighing it in. Trust me, if your ac is all up to snuff and you do a slow charge, right to where the bubbles are gone, it will have the optimum charge, especially if you are without gauges.

With R12 agree, R134 not so much, here, when it hot, if charged to a clear glass, will be significantly overcharged. If charged by weight, there will almost always be foam in the glass.

 

[AMX390]

I'll admit, I'm more of an old schooler, but have been in the HVAC/refrig business for 35 years. The liquid line has always been the liquid line. What good is a sight glass? I'll have to respectfully disagree, and OP's sight glass definitely appears to be low.

 

[Giusto]

The truck is a 94. I haven't done any work on the AC since I bought it a few years ago. I'm not sure if it's R12 or R134. I understand that you can purge all the R134 and replace it with R12.

Can I use the recharge cans at the auto store for this?

 

[AMX390]

Sounds like r12. And no, you can't just dump the 12 and add 134a.

 

[AMX390]

R12 is not easy to find and is pricey when you do. You need to make sure of what refrigerant you have.

 

[Giusto]

OK, Thanks AMX390. I think this is a job best suited for a pro. I'll be taking it to a shop. Thanks for all your help. I understand the system a little more now.

 

[blkprj80]

1994 is R134a. There is a decal on the radiator support.

Your truck looks a little low. Yours is one of the few that could probably benefit from one of those "recharge" cans with the hose you can buy at about any autoparts store. Some people fail because their system is way discharged and has a leak.

When you're putting it in, watch the sight glass, and stop when see it change to very fine bubbles like @Tools R Us says, and the bigger bubbles are gone. I would expect you to use about a half to a full can. Not any more though as it would take just less than 3 of the small cans to fill it from empty.

You will connect to the low pressure port; I don't think you can connect to the high side anyway due to size. Keep the can upright, and put it in a bucket of warm water. Don't invert the can. It will take longer, but it's the much safer method.

Good luck with it.

 

[1972FJ55]

Most manufacturers got rid of the sight glass when they went to R134a because it's not a good indicator of correct charge. Best to start from zero and charge with the recommended charge amount.