Dash heater

[mrwrench]

The dash heater blow warm/cold air .
any thing to check ?
There is no valve control.
If I move the temperature selector I can heard that a door open and close .
I scanned the engine temperature and it runs at 190 degree .
I think the thermostat is fine.

thanks in advance...

[DaNash]

There is almost always a heater by pass valve in place. You do not want the A/C to fight against the heater. Unless the air flow through the HVAC box by-passes the heater core entirely. But with the caliber of todays 'mechanics' anything is possable.

That said...

If in fact there is no valve, the engine is 190 and the blower is on high, but your still experiencing cold or moderately warm air. The problem is low flow, either liquid or air. Your hoses may be full of all kinds of eewey gooey junk or the heater core itself will be stopped up with an excessive amount of dust. I once found a mouse nest under the turbo of a 6L PStroke. It's possable you also may have an unwanted guest in your vents.

Good luck and stay warm.

[gatorv]

Follow your heater hoses and look for valve that shuts off the water so it can't circulate. It's probably stuck closed or restricted. If it is? you can force it open and closed a few times to break it loose. You can also touch your hand on the heater hose when engine is warm to see if its hot or not. If you have a pusher? Mine doesn't normally get hot until about 1200 rpm. Idling will not push the hot antifreeze to the front efficiently. Need to know Model and engine to give better advice. good luck

[House Husband]

Your HVAC is from Denso. NO water valve and NO vacuum controls. All electric servo motors. You system uses a blend door to control temperature. It's not like HR or some other brands.
HVAC Systems | DENSO Heavy Duty

Richard

[mrwrench]

yes it is Denso ,I can't find the blend door.

[mrwrench]

it should be the blend door , the engine , the heater core are hot ..