Air conditioning

I thank they did OK. Worked on a lot more 9670's than 4070'b or a's. Believe they all ran the same box under the passenger seat, the A/C unit that is, as the 4200 and 9370"s. Changing them to R134 the condenser and evaporator would work if in good condition.
Common problems: Heat from the engine. Put water cut off valves on both heater hoses at the engine.
There are two blower motors. unhook them one at a time and be sure both work on all speeds.
Be sure doors are properly adjusted and no padding is missing on top of the evaporator. All of the air must go through it and not around it.
The evaporator must be clean for air flow.
Air for recirculation comes in the back of the box. It must be clear.
All the normal duct work hooked up and working properly. Saw one disconnected under the passenger floor board once. Close off all the air outlets on the passenger side.
Was the entire system flushed out? No mixed up oil and the correct amount? No other restrictions than the expansion valve?
What do the pressures run?

 

I believe those were like this. Remove the cover by the right door and you can see one. The seat has to be removed to see the other one. Do not go by sight as to if both work. One can blow air through the other and make it spin. The blower control has one lever with two switches behind the panel. One for each motor. High speed is though a relay for each motor under the seat.
Heater, defroster and A/C use the same two blowers.

 

I switched my 92 over to 134 a. No need to change hoses or o- rings. All that hype while technically true. Was a bunch of bs. It worked great for years afterwards. Supposedly the old hoses would leak through, and silicone hoses were needed, also old silicone o rings would be eaten in no time, therefore vitron o rinds wee needed. All bs, if 134a eats silicone o rings, why not silicone hoses. Think about it. Dealers were charging $1000 in 1997-98 for the service per technical bulletins, I converted mine for less than $25.00 it worked great for years

 

Some of the old systems used mineral oil and you have no idea how much is in it. Some oils mixed together make mud. It is a good idea to do a total system flush and start fresh. I saw many done like Rideandrepair that was fine. Others lost the compressor.

 

The kit I used at the time was an Interdynamics brand, I had all new hoses and condensor recently, wham my Sanders compressor went out @ almost 1 mil miles!!! Yes it lasted that long. So I decided to switch it over, problem was that included a more expensive compressor w/o fittings and replacing lines with in line fittings. While explaining all this to my brother in law, who worked at Murray’s auto parts ( O Reilly’s ), he called BS stating the kits were on sale currently for $20 , it included a hose, 4 cans of 134a and a can of estrol oil which was compatible with all oils. So I purchased original compressor w/ fittings.( cheaper) and the kit. I agree anytime you change a compressor, the exact amount of oil is unknown. Sanders suggests draining oil from both old and new compressors and refilling new one with the same amount that came out of old one. It’s not a very exact science, oil level. They suggest leaning on the lesser amount rather than too much oil, surprisingly, due to too much oil displacing the gas, and causing the compressor to run hot and shorten life. Something I learned recently, while converting my current Freightliner from a York to Sanden compressor. That was a surprise, prior Jobs I’d done, I would add oil, thinking it might hurt cooling, but help the life of the compressor. Turns out the compressor relies on the gas to cool itself. Very complicated stuff. Always something new to learn, I’ve done my Own for 20 + yrs. Just when I think I fully understand, Something new comes to light. My apologies, Looooong post

 

I’ve got to say, the fact that you have knowledge of the old Internationals is impressive, you must be an old ######!!! Just kidding. I’ve heard they are unique in design, but easy to access because of being under the jump seat. I have a catalog full of part #s if anyone ever needs help with part #s. Every Truck a/c part ever made.