Forum Discussion

Explorer

Jul 29, 2015

ENGINE A/C PROBLEM, NOT ALWAYS COOLING

We have a 2006 Coachmen Aurora Class A motor home with a Ford F53 chassis and a 6.8L V10 engine. We are having intermittent problems with the engine A/C system. We've evacuated the system (3 times), replaced the dryer and expansion valve, but still have a problem. When the expansion valve was replaced this week, the air coming out of the vents was 36-38 degrees when checked by the mechanic. When I picked up the motor home and drove home, the air from the vents was approx. 62 degrees. The pressures are holding so I don't have a leak in the system and the coach only has 16,000 miles on it. I was wondering if we may have a problem with either the vacuum for the door or the door is catching when trying to shut off the heat side of the system. I've been trying to find more detail about the Evans Tempcon system and did find a pdf that show the major system components. Anyone have any suggestions where we go from here? I don't want to keep chasing parts. Thanks for any help you can provide. Service center for this a/c system is a solid 3 hr. drive away.

15 Replies

Ranger_Smith
Explorer
Jul 29, 2015
It is usually mounted under the hood on the ac box and has a copper probe that goes into the box
Coachmen63
Explorer
Jul 29, 2015
Good question about the freeze sensor, but I'm not sure if it has one. Sounds like there is more to this system than meets the eye. Any idea where this sensor may be located? May be an unfair question because coach manufacturers put things in different locations.
I'm fairly mechanical and do a lot of work on our coach myself. Learned a lot from working in a true "filling station" when I was younger. Kept up the skill.
Ranger_Smith
Explorer
Jul 29, 2015
Is there a freeze sensor on that. I had the same problem with that ac unit. Bypassed defective freeze unit and it is working like a charm
Coachmen63
Explorer
Jul 29, 2015
I clamped off the hose ahead of the cold/hot valve and it didn't make any difference in the coolness of the air (this was suggested on a Tempcon site). So it appears the valve is working properly. I switched the valve to heat and the air definitely got hotter and when I switched it. I heard the door switch, but it sounded like it closed hard, like it might be sticking and that is why I'm thinking we may have a door switching problem or vacuum to it.
sch911
Explorer
Jul 29, 2015
Make sure the heater control valve is properly closing off hot coolant to the heater core. If there is a vacuum leak the system would start blowing from the defrost outlet instead of the vent outlets when under low vaccum operation such as heavy acceleration.