No heat in bunk
 

I have a few questions and I have a feeling they are related some how. The AC in my bunk works ok but no heat. When I opened the hood I notice two valves and I think one goes back to the bunk. They are connected to the block heater. Can someone explain what those valves are for and why they are there?

Bad Thermostat?

Open the heater valves in the fall, close them in the spring :wink:

They are designed to make your A/C system work better, by blocking the coolant from going to the heating system.

BD has it right - open them in the fall, and close them in the spring.

Those valves are close to the engine block heater. When it's plugged in, is there an electric pump circulating the water? I understand it keeps the water at 160 degrees. I also assume this flows to the bunk heating system? Would this keep the cabin warm if the fan was turned on? Anyone have an idea how long the batteries would last running the bunk fan?

Not very long.

The valves are installed for 2 reasons
The heater control valves are not high tech and don't work well
by turning the valves off no water circulates so no heat in the heater core...( some the heater core and A/C evaporator are 1 unit the rest they are stacked on top of each other) some trucks have 2 or 4 shut offs ...2 one for the sleeper and 1 for the cab.. 4 two for each

Reason 2
heater hoses have A habit of leaking or getting holes in them...Mainly reason 1

As far as the block heater it will keep the water warm ....there is no water circulation

Good Grief-Can't believe I forgot the Faucet handle :oops:

The engine block heater barely keeps the water temp at 80 degrees, BUT that is enough to make the truck start in the winter, there is NO circulation pump on the block heater.

As far as the batteries lasting with the fan on, maybe 3 to 4 hours.

Just a follow up here. I was looking at the engine yesterday and found 2 more valves and turned them on and bingo, heat. The 2 valves I turned on before were connected to the block heater. These 2 new valves I found were buried down low connected to the water pump. Not sure what all these valves are for now?

If you follow the hoses from the valves, you'll find that there is a valve at each end of each line. Two lines going to the heater cores. One for the front heat (cab) and one for the sleeper. I could be wrong, but I believe that they were actually put there so that when there is any work done on control valves or replacing cores, you can shut off the water while you break the connections and don't have 12 gallons of coolant running all over. They do make it better in summer though. The control valves restrict or open the flow, but do not shut it off completely. When it's 90 degrees out, you don't need any heat, so shut them off and enjoy the full AC.

Yes, you are exactly right. I followed them are they are exactly like you said. I can see myself turning them on and off depending where I am during the year. Sounds like a pain. I may look into some electronic valve.

Thanks!