I have an 85 Crew cab that has a 93 Dodge Cummins drive train installed in it. The person that did the conversion used everything off the 93, dash, wiring, heat/a/c, radiator, condensor....overall they did a pretty nice job with the coversion. When I got it the a/c had R134a in it and it worked poorly. I charged it and it worked ok, but the back seat passengers were uncomfortable. My future plans include tinting the back and side windows to help keep the cab cooler, and getting new seals for all the windows.

How does the a/c work in 84-85 crew cabs that are unmolested with r12? Great, or mearly ok? I replaced the fan with a new motor and cleaned the cores and the air flow is still marginal from the ducts. Did the crew cabs have different stuff then a 93 standard/extended cab? I'm thinking of calling Vintage air, or even just putting a larger condensor in from an Excursion or van, and trying to put a rear unit under the seat for the passengers in the back......has anyone here done anything? 90+ degree summers with 90%+ humididty, 3 kids and a wife, and it needs to be cool in the cab.

Michael

Is the 93 condenser still a tube and fin style? I believe it is.. I would go with a newer parallel flow condenser with the 134.

I remember riding in the bck seat of the family car growing up, andnever was as cool as the front passengers got.

I have the same setup as you and have had the same problem. First make sure the basics are in order, full charge, underdash box not full of leaves (sounds like you covered these), and most important, make sure you have air flow across the condensor (ie fan clutch working). If everything is in order, check to see if A/C clutch is cycling off before it gets cold. If it is, the temp sensor in the return line might be out of spec. Try pulling the copper line that goes in to the return line out a little until the clutch stays engaged. Once the return line starts freezing up, you've pulled it out to far. These systems are far from adaquate and work even worse in ramchargers. My crew cab's A/C is decent but if I go out to the low desert (100+ degrees), it sucks. You might have a great idea of upgrading to a modern system. I have older systems too and they don't work any better.

Good Luck
Mike

Thanks guys. I had a belt squeak that I tried to fix with a new belt tensioner yesterday, only to find out it was the compressor that the pulley wobbles around on, so I'm going to switch compressors. It explains why when I charged it and made it cool, it only worked for one day and quit.

I'm going to stick a spare compressor I have for it and get it charged again. Hopefully over the winter I can sound deaden the cab and maybe upgrade the a/c. I just wanted to make sure that the stock system wasn't better then I have now.

Michael

Study up on how the system works on mini vans or suvs. Seems some run a separate condenser or insulated ductwork or both in the rear.

There is a large volume of air to cool down in the crew cabs - similar to Ramchargers of the same vintage.

Even after optimizing the A/C system in my old R/C, it would still take a while to pull the cabin down to temperature, but eventually it would get meat locker cold. R12.

After ensuring that everything is working well on your A/C system, it would be helpful to install reflective insulation between the carpet and floor pan to slow the rise of heat up into the cabin from the road and exhaust.

Ditto for installing a headliner if you don't have one. A Ramcharger 1-piece headliner can be cut and trimmed to fit the crew cab and also helps with both noise and moderating temperature.

My 85 crew has a Cummins conversion done to it, and last week the belt started squealing. I thought it needed a new tensioner, but I found the pulley on the compressor was the culprit. I bought a reman compressor, replaced it, vaccumned the system down and then added R134A to the system. I backed it out of the shop and finished filling the system. Temp check showed I was getting 32*F air out of the duct on the passenger side. That day I took it for a drive and the front people were comfortable, but the back seat was still noticably warmer. I guess I'm going to pull the dash back apart, and make sure all the duct work is sealed up and hooked up, as air flow was pretty miserable out of the vents. The other mod I'm going to do is put a relay that switches on when the fan switch is on "high". That way the fan motor sees true battery voltage to get a little more speed then the typical voltage drop a person sees through the switch.

I think the cooling part may be up to the task with the fact of the cold temps even with R134a in the system, its just a matter of getting the air moved around the cab.

Michael