09 prostar a/c replaced everything still not working

Prostars have 3, (three) sensors. Two temperature sensing thermistors for evaporator in and out temps and 1 pressure sensor on the high side.

 

That's good to know

 

Yesterday the front blower on my 2012 Prostar with only 85k doesn't come on at all heat or AC and the compressor doesn't engage. The rear AC fan works but with the engine on no cold air. Rear is only cold running APU. I contacted a dealer near my next receiver but they tell methey are 4-5 days out. Man this sucks! Any ideas? Another driver told me about a relay problem. Anyone concour? Were is the relay located?

 

There are two fuses that feed power to the hvac controller, (the unit with the dials on it). F4-L(should be a 10 amp breaker) and F1-B(should be a 5 amp fuse), that provide power to it. Make sure they are good. Sometimes the terminal inside the fuse block starts to get weak and makes poor contact with the fuse or breaker. Try to wiggle the wire from underneath, or see if the wire itself has come loose. The fuse panel is located directly in front of the passenger seat. It is the panel with the "International" logo on in. The panel just pulls off. There should be a sticker on the back of the panel with a diagram on it with the fuse and breaker locations and descriptions.

 

When I made the last post I was at a truck stop doing a 34. When I started to drive the cab HVAC started to work. However on the normal AC position, no MAX. WHenever I stop so does the AC. I'm thinking sensor or?

 

When ever your a/c isn't working when stopped, but works when moving we need to know if the fan is coming on or not. If the fan does not come on when you are stopped the condenser at the front of the rad with get too hot, a/c pressure with be too high. The a/c will shut down, and/or the refrigerant doesn't fully change state from a gas to liquid over the condenser, both of these will cause the a/c to be weak or none at all. Prostars only have one pressure sensor. I may be going bad. If your truck has a a fan override switch, try to leave the fan on when stopped and see if the a/c starts to work. The only difference between "Normal" and "Max" a/c is the position of the recirculate flap between fresh air and recirculate. The a/c works the same between the two modes. In "Max", you are just recycling the inside air, and blocking off outside air so you continually recool the cooler inside air to ultimately get colder air in the cab. There is a cab filter inside the cowl at the firewall that may be starting get plugged up. If they get plugged it will slow down overall air flow across the evaporator and cause weak a/c, but shouldn't prevent it from working.

 

The fan doesn't come on in the cab while sitting still. It does come on in the sleeper, blowing cold, when I discovered this I opened the hood and sure enough the clutch on the compreesor was engauged. I tested the Max AC again. While driving down the road I got the AC on normal, blowing cold. Switched over to max fan quits no cold air at all.

 

Sorry, I was talking about the engine fan. If the heater blower quits at max I would say the hvac control module is buggered up.

 

I had 2 thermistors switches replaced along with both shrader valves in the ac lines. Vacuum and recharge after diagnose for the ac that was not working properly. Had it done at a non international mechanic shop. Plus or minus a couple hundred dollars what should that generally cost.

 

Heavy D,
You seem very knowledgeable with this AC problem on these Prostars.
I have a 2009 and have been experiencing the thermistor problem this year.
My normal shop doesn't know of the upgrade in the software and I'm not sure they are using the best quality thermistors.
In the last three weeks, we have replaced two of them.
So, after reading your post I called Rush Truck Center here in ATL and asked them about the upgrade in software over the phone. Rush is listed as the number 1 place to go in ATL for International trucks on the International website. The problem? He said he wasn't aware of the software upgrade.
Anyone around the southeast you might know of that could really get this thing repaired correctly?
I'm in a bad way here with a lot of money lost...can't afford much more.
Any part numbers for the high quality thermistors?
Any help would be greatly appreciated.
Thanks,
68 Goat