New to Mazda’s and am not familiar with the PTC heater. The fuse in the dash is blown, replaced and blew as soon as I turned the key on. I just purchased a 1986 B2000 very clean and well kept. I noticed a big change when I replaced the hose that goes from air snorkel to the heat shield on the exhaust manifold. I know the stock carbs are junk and there is a Weber in the plans.

So back to the subject at hand, the elusive PTC heater. Also temp gauge in dash is in op, I also noticed lower radiator hose was not as warm as it should be, so probably needs a thermostat also.

So thanks in advance for any help.

 

PTC heater?

 

On the bottom of the dash fuse panel there is a 20 amp fuse marked PTC heater. So that’s my question also, what is it/where is it.

 

The PTC heater is between the intake manifold and the stock carb, pre-heats stuff when the weather is colder. I removed my PTC on my 1988 B2200 when I went Weber in 2005, must still have mine sitting somewhere. If you unplug the PTC heater electrical connection on the engine and the fuse doesn't blow, then your PTC heater has a short, up to you whether to replace it.

I think your immediate issue is that you did not get all the air out of the cooling system when you replaced such hose - this air bleed out is somewhat difficult to do on these trucks. I jack up the front end, remove radiator cap, turn heater on, and run the engine, topping up with 50/50 as necessary; this bleed out of the air might take 20 minutes. Then cap radiator, turn of engine, lower, etc.

Your thermostat may be fine. I run a Stant 192/195F here in Arizona and do not run hot, but mine has a replacement radiator as well, and 215K miles.