Nissan Repair: 2005 Nissan Frontier Heater issue, oil pressure gauge, vacuum problem

Question
Hi,
The heater in my '05 Frontier (4.0 V6) only blow hot air if accelerating or at least when keeping a steady speed and the engine is running at higher than idle rpm speed.  If I let off of the throttle to coast to a light, or just to scrub some speed then the heater will quickly begin to blow cool air.  This happens at any speed so it seems rpm dependent and so it would seem to be a vacuum problem but I really don't know.

FWIW the oil pressure sensor seems to have malfunctioned at the same time as it it pegged high even when I just turn the key.  Coincidence?  Probably but I thought I'd mention it.

Thanks in advance.

Answer
Hi Jon -

I would appear that you have some restriction with the valve that controls the hot water from the heater. Follow the heater hose from the engine and you should run into an in line valve. Check the vacuum source and line for cracks or leaks. Also check the valve for binding.

Does you oil pressure gauge needle move higher when your idle is higher? Perhaps you will need to replace the sending unit.

Hope this helpa -
aloha
calvin