I always smell the unmistakable odor of antifreeze when the dash heater is on. I do not see any evidence of a leak. Cummins Northwest tested the cooling system by pressurizing the system and found no evidence of a leak. The induced pressure did not drop during the test period. I am thinking that I should disassemble the heater and look for evidence of a small leak (small leaks will become big leaks). Has anyone disassembled their heater to repair or replace the core and if so, is it a difficult procedure? It looks like a daunting task but I might do it myself with encouragement from someone who has been there. Comments will be appreciated.
Gary
We found our heater core leak by permanently hanging a plastic container so the dash air conditioner evaporator condensate rubber drain hose empties into the container. When the fluid collection measured freeze protection using an inexpensive tester, we knew we had a heater core leak. Plain water collected would be normal condensate.
Condensate drain on our coach is just to the left of the generator when looking in toward the rear of the coach with the generator door open.
We then put ball valves on the heater hoses (to the dash and from the dash) at the street side of our Cummins engine. We closed the new ball valves and drove for several summer months until we could change out the heater core.
The center of the dash comes out after removing several wood screws into the floor and into the adjoining dash sections. This exposes the metal box housing the heater core & air conditioner evaporator coil. The air conditioner pressure hoses had to be disconnected and refilled with refrigerant after the heater core was replaced.
Gary,
Here is a link to a thread that may have some info that will help you out. We were talking about a U-270 but a lot will apply as the dash comes apart the same. With you having a U-320 the big difference is you have a Aqua Hot heater core that is hid in there. Have you been having to add more antifreeze to your A/H unit lately? If so this may be the reason a pressure test on the engine coolant system didn't show up a leak.
Replace Heater Core 98 U270 (http://www.foreforums.com/index.php?topic=22762.msg174525#msg174525)
Pamela & Mike
Barry, does yours have a split system (separate heater core and A/C evaporator) or a combined system (heater core and A/C evaporator in one unit)? I just ordered one from FOT and Billy Jack told me ours is a split system. I was surprised, as I have never had a vehicle that had the units combined. I am hoping not to have to disconnect and A/C hoses to do the replacement!
Don
Don, our dash had separate heater core and A/C evaporator. I was not aware of combined units, although autos may have such an item for efficiency.
There are heater hoses and coolant lines visible on bottom left side of our dash circuit breaker panel.
When I did ours, I didn't have to disconnect AC hoses. Pinched heater hoses, no leaking (but some drips).
Heater core replacement (http://www.foreforums.com/index.php?topic=10000.msg45564#msg45564)
Thanks Dave, that is helpful to know! I received the heater core from FOT today, wondering if I should maybe pressure test it before I put it in or trust that it will be good to go ::) . It seems that it isn't that tough a job, but tedious to be sure. For sure a good idea to take a few pictures as I go to supplement my memory. Thanks for the link to your replacement. I am hoping I will find my AGS module when I tear into the dash!
Don