I have a 1991 dodge cummins that I bought over the winter. The AC was out of coolant when I bought it, but that was not a big deal because it was winter. Now it is getting hot at I am trying to charge it. I have a can of r-12 replacement that came with it but the fittings on the hose that I had are for are to big for the system. How Can i charge my system? Where can i get an r-12 hose? And which side of the ac system is the low pressure side on the first gen? please help me if you can.

 

You are probably looking at an R-134a system, so that's why the R-12 fittings don't fit. IIRC, the switch to R-134a had taken place long before 1991, but I could be mistaken.

Good luck. I spend many hours and dollars trying to repair/charge the A/C in my '91 before finally giving up and pulling it out. A non-IC belt was about the only thing it needed after that. Between losing that and the brush guard I took about 150lbs. off the front end.

 

So I guess I have the wrong can of coolant because the hose I have is for 134a but the fittings on that are bigger than the one on the can. Which side of the ac system do you hook the hose to when filling it up.

 

You charge it on the low side, but a better question to ask might be "why is it low in the first place?"

 

X2. And how low is it? Filling until its cold is not a very acceptable method in my eyes.

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The switch began in 92. If the system is still r12 you will have a big and small screw on type service port. The low side is right next to the firewall, and is bigger of the two. R12 gauges and filling hoses are all the same size. Your high side is smaller so "some people" can't blow up the refrigerant can by trying to charge the high side. If desiring to switch to R134A the already lacking hvac system will leave you in a sweat! And to do it right you have to flush the system, replace the compressor, and hoses. R12 hoses will "leak" 134 because the 134 molecules are smaller. I've done many conversions on tractors. It makes it not so hot as outside but not comfortable.

 

It is completely out there is no cool air coming at all. Cumminstagetcha19 my hose won't fit the can I have.

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I just looked at the can I have, it's called freez 12 not r-12 it says it replaces r-12.

 

my 91.5 had r12 fittings on the lines. i replaced them with r 134 fittings years ago. you should find a friend that has gauges so you can see what is going on. my 91 really has a good ac in it.

 

That replacement is probably a mixture of propane, 134 and leak sealer. Not only is it a good way to mess up your system but it is illegal. Google r134 and r12 service connections. They are unmistakeably different. If it is completely empty you have a bad leak. Check to see if the compressor clutch cycles, it may be severely undercharged.

 

Let me know if you need any parts. I have an unused condenser, compressor, lines, etc. taking up space in my garage.