Heater/Defroster Problem

[mxz600]

Hello fellas,

Hope someone can help. Now that it's gotten cold here, the
defrost in the 84 K20 works good, blows good and is warm not hot. The heater blows good, but is nowhere near hot, in fact,
it is cool.
Anyone have any ideas? I thought you only replaced the heater core when it leaked. Do I need a new one?

Thanks in advance.
Jay

[Kopper]

Just a couple of things to check:

- what temperature thermostat do you have, I'd suggest running the stock temp.

- it's possible that your cooling system needs a flush, you can always just flush the heater core if you want, disconnect the heater hoses and hook a garden hose to it.


Ken

[mxz600]

She runs 180 degrees all the time, 80 degree summer
and 10 degree winter. Doesn't get any better with the
plow on it either. Probably will do a cooling flush. Don't
have any idea what condition that's in.

Jay

[86-C10-V6]

You may want to check the cab controls and make sure the diverter doors in the duct work are moving where they should.
There is one door that controls where the air goes, i.e. floor, vents, defrost.
There is a second one that controls the amount of air coming through the heater core. This one may no be moving all the way to heat.
Of course this needs to be checked in addition to the heater core circulation.

[Piston]

Do a quick test...

Warm the engine up to full temp. Next you'll need to feel both heater hoses. Tell me if:
Inlet hose is hot / outlet hose is hot
Inlet hose is hot / outlet hose is cold
inlet hose is cold / outlet hose is cold.

From this info I'll be able to let you know where the problem is.

[old Rusty C10]

i would check the doors first unless its been a real long time since you flushed the coolant; i know that on my truck the cable rusted and it locked out and i had no heat

[mxz600]

Doors all work fine, fixed those when I had the dash apart
to fix the headlight wiring disaster. I will check the in/out
lines tonight after my ride home from work.

Thanks will let you know what I find out.

Jay

[Kopper]

Jay,

I'll assume that you have a 180 degree thermostat. I have previously ran a 180 degree thermostat and this year changed back to the stock 195. I don't drive my truck in the winter but I really noticed the difference in the amount of heat that the heater put out this fall. I also noticed an increase in gas mileage.

So do you have enough snow for the MXZ600 yet? We've got a few inches on the ground.


Ken

[mxz600]

I do need to change the water neck, so I can change the
thermostat to see if that helps after I flush the coolant
system. Can I tell what thermostat I have visually, or
should I just spend the few dollars and buy a new one?

Not enough snow for sleds yet, but we have the annual
grass drags coming up Saturday. Can't wait to ride it
again, have 3 miles on in the grass already just tuning.

Thanks,
Jay

[Kopper]

The temperature is stamped on it but I would purchase a new one anyway.

Ken