Once again I’m diving into a system I know very little about. I was going to wait until after I painted to do the ac/heater work but I realized that was dumb and I’m not going to paint the firewall so I’m going to go ahead and tackle it. Heater part is no problem. I’ve purchased new a/c lines, new drier, new orifice tube, new evaporator, and new condenser. I’m going to see if I can get the old compressor working because of how pricy they are. Also after doing more research I realized that the tube and fin condensers aren’t ideal for switching to r134 so if someone knows of a parallel condenser that fits well with the same fittings I’ll take the one I just bought back. Also I know the low pressure switch can and should be adjusted with a screw between the terminals because pressures are lower with r134. So if someone has experience with that I’d like advise. Finally I still need to hook up the vacuum line that goes to the heater box. So I’m starting this thread because I’ll definitely run into problems and need help. Also any information about switching from r12 to r134 would be helpful. Thanks in advance!
CK5
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A/C system revamp
- Thread starter Jake_C_
- Start date
I put a crossflow condenser from O’Reilly’s on my 1987 Suburban. It fit into the mounts correctly and the hoses connected right up. My 1st one lasted almost 4 years and 20K miles before it developed a crack. They replaced it under warranty and all is well again.
Your current condenser will work with r134. You sure you want to try an old compressor with all those new parts?? what type/model compressor do you have?
what year are we working with ?
what year are we working with ?
Thanks a ton for that diagram that will definitely come in handy. No I’m not sure I want to reuse the compressor but I figured I could a least try it and maybe save money. Not a good idea? You can maybe tell the size from the picture but I can get a better one tomorrow.
That’s all the info I have on it not sure what happened to the part number.
nitro_rat
1/2 ton status
That's a R4. New GM ones are available from Rockauto and others. The new ones are much quieter than the old ones or most remans. Old R4's are known to "rattle." They aren't shipped with any oil so you have to add that to the system or they'll lock up when you try to charge them. One 8oz bottle of PAG150 will do it. Put about 3oz in the compressor and turn it several revolutions. Put 1oz in the evaporator, 1oz in the condenser, dump the rest in the accumulator/receiver/drier.
Be sure to flush out any old components you don't replace prior to adding new oil. Denatured alcohol and compressed air works good. I always replace the old hoses, unless you have a Suburban with rear AC the hose assemblies are available and cheap. 134a requires a barrier type hose, the 134 molecules are small enough to permeate through the old R12 hoses.
Be sure to flush out any old components you don't replace prior to adding new oil. Denatured alcohol and compressed air works good. I always replace the old hoses, unless you have a Suburban with rear AC the hose assemblies are available and cheap. 134a requires a barrier type hose, the 134 molecules are small enough to permeate through the old R12 hoses.
nitro_rat
1/2 ton status
oh, and use a Ford blue orifice when converting to 134a!
I’ll go ahead and pick up a new compressor then. I think every part of the ac system will be new after that. Thanks for the information on the oil that helps me out. I did get new hoses so hopefully we’re good there too. What’s wrong with the stock orifice tube? That’s what I bought. As far as the order of recharging the system I want to make sure I have this right. Hook everything up obviously, pull vacuum on the system and make sure it holds for like an hour. Then run the vacuum for another couple hours. Then go through the filling process.
The blue ford orifice tube suits the r134a pressures better than the GM r12 tube. I am glad you decided to get a new compressor. The vacuum plan is a little over kill. an hour is good, since all new components, theoretically sealed until install. Be sure to use a new unopened bottle of oil.
Also before you install the new compressor there maybe oil in it, drain it out before you add the new oil. This way you know how much oil has been used.
Also before you install the new compressor there maybe oil in it, drain it out before you add the new oil. This way you know how much oil has been used.
The blue Ford orifice is .068" diameter. The white GM orifice is .072". R-134a is smaller at the molecule level than R-12. The blue orifice will get you colder at lower engine speeds than the white one that is in the truck will. There is also a red Ford orifice that is .062". I tried that on my Suburban last summer and didn't get better results at idle and had less cool air going down the highway. But, mine is a dual front and rear system so really an apples and oranges thing.
I have the blue Ford part in mine and have for the last 4.5 years. I also tried the white GM unit and lost a few degrees at idle and highway speeds.
I have the blue Ford part in mine and have for the last 4.5 years. I also tried the white GM unit and lost a few degrees at idle and highway speeds.
Ok I’ll do all that. So I dump all the oil in, seal everything up, do my vacuuming, and fill the system right? That’s the correct order?
Interesting, I’ll pick one up today. Thanks for the info!
Is this the right one?
I couldn't find that part number on the Autozone site. Just punch in a 1994 F-150. You want the non adjusting blue orifice for a stock 1994 F-150. Well, pretty much any Ford from that era.
Need to move the valves from inside to outside for gauges to work.
Put the valves in the adapters?
yes, most of them come with valves in them. That way you have two valves to open and
close by the gauges. I always take the inner one out.
close by the gauges. I always take the inner one out.
Ok I want to make sure we’re talking about the same thing. The low pressure port on the receiver/dryer has a schrader valve and the new adapter fitting I got to allow the r134 fitting also has a schrader valve. So I figured on that one I just remove the valve on the receiver/dryer and install the adapter so that there aren’t two valves. On the high side port however the adapter fitting doesn’t have a schrader valve so it would have to use the old valve and im not sure if that’s right or not. Hopefully that makes sense.
Yes remove the inner shrader valve. If you try to put the adapter on it will probably damage the inner shrader and not get tight
Ok thank you that’s what I thought.
