Heater on dash turns off every now and then

[Eddy_smith]

My in dash heater on my 2016 class c motorhome with a Ford E450 Chassie turns itself off intermittingly for about 30 seconds to 2 minutes . It does it on straight highways, climbing grades, going down grades, city driving, It just does it.

Took it to Ford six months ago because it was still under their warranty. They claimed they could not duplicate the problem. Not really sure what that was going to do. But since it was going out of warranty they claimed they replaced the entire heater assembly.

Anyways worked fine up until now. Same problem.
Anyone have any ideas?"
Thank you

[dougrainer]

I would suspect the 12 volt power for the AC/Heater unit is on a auto reset 12 volt circuit breaker and that breaker is either undersized or is weak. Ford usually does NOT install a Auto CB but a 40 amp fuse. Somebody may have changed out the fuse with the Auto reset CB. Doug

[Eddy_smith]

sch911 wrote:
IF it's going to defrost it likely has a engine vacuum issue. That's what drives the HVAC mode positions. Many times the reservoir is bad.

No it does not go to defroster. It just shuts down. Blowing cold air, and after a few seconds or a minute or so the heat comes back on.

I cant seem to figure it out.

[sch911]

IF it's going to defrost it likely has a engine vacuum issue. That's what drives the HVAC mode positions. Many times the reservoir is bad.

[Kamphiker]

is it going to defrost mode ?
(Air changes from dash vents to blowing on windshield)