Front AC/Heater Questions

[smo99]

I have a 2008 Berkshire 390QS purchased used last year. Still learning..

First dumb question: What do you call the forward mounted AC unit that's under the front dash? And who makes it?

Mine works pretty well for a while and then it just stops blowing air (although you can hear it the fan). It seems as if it ices up and no air gets through--and what little that does is hot.

Is it time for a new unit? Is there something I should clean out?

I've also noticed that when you want heat from this front unit, it's best to start the coach, let her warm up and then warm air is possible. If you try to get heat starting out cold, it never warms up. Is this normal? I recall being told it pulls heat from the engine and if you don't let it warm up, the tunnel will stay cold on a cold day. I'd like confirmation...

Thanks!

[ceedog]

smo,

Congrats on your new to you coach. Now to the issues. Have you had the AC recharged? With it being a 2008, it's 8-9 yrs old.

With your heater, you're right it does pull heat from the engine, hot water/coolant runs thru the heater core which the fan blows thru thus producing heat. Have you checked your coolant level?

[NV245]

Sounds like evaporator temp sensor failure, it cycles the A/C clutch to prevent condensate on the evaporator from freezing, I've already had two replaced. The heater does use engine coolant, the engine does need to be warm for heat to be produced out of the chassis HVAC unit. Hope you enjoy your new coach.


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[TwiceTheIce]

I believe there are valves in the heater hoses back near the engine. If closed or partially closed,this will prevent you from getting heat.

If, in certain climatic situations, you continuously operate your dash air in the max position, you can freeze the condenser and block cold air flow.

[Berkshire Driver]

Do all of the vents stop blowing? or is it one area like driver or pass side or do defrosters blow when vents stop if def blows then the control is not working properly most go to defrost in default if control fails. i beleive the heat does require the engine to be running. have the refrigerant checked a sure sign of low refrigerant is compressor clutch cycling off and on rapidly.
ours has a vacuum motor in the driver side outer compartment if you have this check it it may be out or a fuse to it.

[accumack]

I've had any intermittent problem with the dash A/C It seems to be a sensor. On hot days there is no way the dash unit can cool the coach so you need to run the generator and the roof unit. The heat takes quite awhile because the engine has to be up to temperature and it has a lot of coolant to heat.

[tmmar]

Originally Posted by accumack

I've had any intermittent problem with the dash A/C It seems to be a sensor. On hot days there is no way the dash unit can cool the coach so you need to run the generator and the roof unit. The heat takes quite awhile because the engine has to be up to temperature and it has a lot of coolant to heat.

A lot of coolant to heat and a long way to travel. Must come from the back end of the coach to the front.

[smo99]

So it sounds like the heating may be "normal" and if we do let it warm up before getting underway, it works great.

The AC may need a recharge and or some of the sensors may need checking (sounds reasonable!).

Berkshire Driver, yes, all the vents stop blowing on those hot days, and we do run the genni with the roof ACs to cool the rest of the coach...we knew that little unit couldn't possibly cool that volume of air :-)

Thanks for all the info...much appreciated!

[jbramhall]

My dash AC system has a coolant leak that neither I nor a professional shop was able to locate. We used that ultraviolet dye that you add to the refrigerant lines. There must be a pin hole leak somewhere between the AC compressor in the engine bay and the evaporator in the front near the dash. That's like a mile (!!) of refrigerant line, and it's insulated and hard to inspect and diagnose.

I travel with 2-3 cans of refrigerant and top off the system with a can before I travel in hot weather. It's a pain in the butt to remember to do this, but not too difficult or time consuming because the valve is located high up in the generator bay.

It seems like the system will retain the refrigerant better when it's in use. Once topped off, the system stays cool for a trip, say, a 1-2 day drive followed by a 4-5 day stop. It usually will be good for the return drive. Then, if the coach sits for a couple weeks, I'll need to top the system up again before the next hot weather ride.

I agree that, to cool the coach, the dash AC is insufficient, but I have a wife who does not like AC; so, to stay off the couch at night, it's worth it to make the dash system come on and keep me cool as I drive while she enjoys her tropical setting at the dining table in back.



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