Bunk heater

If you're talking about the heater you use when the truck is off, most heaters only run to one outlet. It can be plumbed to exit to more outlets.

An auxiliary bunk heater will rarely put any heat out of the trucks vents unless it gets plumbed in. You can try changing the angle the output vent blows to. It should spin in place.

Just crank it up and you should get some good heat. They generally work pretty good.

 

That's how it works. A diesel fired bunk heater only blows heat out of the vent near the floor. I have a Webasto in my Volvo 730 and it works well enough that I did not have to idle my truck one night last winter. In fact, rarely had to crank it up past the half way mark.

 

They work well enough that I have used only the bunk heater to as low as -40C (also had a separate engine heater, so no idling required).

 

Your bunk heater may need servicing and repair. It may have an ignition issue or a fuel blockage. The bunk heater fuel pump may not be working properly. You could even have a Volvo bunk control panel issue. Bunk heaters are easy to troubleshoot and service for a mechanic who is familiar with them.

Note re bunk heaters:

In Canada bunk heaters should be mandatory. It's unbelievable that there are still tractors without bunk heaters. Idling at a truck stop should be illegal and subject to a billion dollar fine. It drives me nuts when I am sleeping and Fred Flintstone pulls up and idles his truck all night because he does not have a bunk heater, ruining the peace and quiet and a good night's sleep for everyone else.

Idling clogs up your diesel particulate filter, wastes fuel and harms your motor.

 

I guess I'm lucky and my company truck's bunk heater has hot air coming out all the vents in the cab though AC only comes out the bunk vents on EPU.

But I do have to wonder in July where is this a big issue?