So in my 93 ranger im trying to diagnose a no heat issue. jere's what I've done already. Ive replaced the thermostat, flushed the heater core, and I cleaned out all the ductwork. My temp gauge fluctuates from just above the "n" mark to the bottom of the gauge. I also noticed that on vent it blows out more air than when its on panel. Would a coolant temp sensor cause the fluctuations? Any help is appreciated

 

After the engine runs a while do both heater hoses get hot?

 

I let it run for about 20 minutes, the top hose was hot. The bottom one was warm not hot but definitely alot cooler. Could my water pump be going out?

 

If you are sure the blend door is not letting in too much cold air, I would confirm that first. If operating properly, then there is a good possibility the heater core is restricted with junk.

 

I agree with Hanky. I would also consider this, How much higher than the engine and water pump is the heater box and core? Those with heater cores higher than the engine, etc. are notorious for air-locking or, having an air bubble in the core not allowing it to fill with coolant. I would probably loosen the cooler of the two hoses (break loose the seal between the hose and core tube) and with an assistant, start the vehicle and assure coolant flow from the core. Or, cut the cooler of the two hoses and put like a flush tee on it. Then you can just loosen and tighten the cap on the tee to assure flow.
Just my opinion, ... hope this helps.

 

I think Rich73Kelly has a good idea because some heater hoses have special fittings where they connect to the heater core and without the proper tools they can be a problem to remove.

 

Why don't you just try the old fashioned flush of the heater core with a garden hose? This can tell you very quickly what the flow is like; these system were notorious for clogging cores up.
If that's ok, then run the truck with the cap off till it gets good and hot (t-stat open) and see if the coolant in the radiator bubbles a lot, or even if the heat comes back to a more normal state. If it does, and there's a lot of bubbles, it could denote engine problems.

 

Hello Greasmark, welcome home !

 

Thanks for all the input. My heater core is indeed higher than my water pump. So I will check for an airlock. I already flushed it out with a garden hose. I had full flow going both directions. I'll try everything else and let you all know. Thanks guys

 

So I spent some quality time with the ranger today. Took the radiator cap off and no bubbles. But the heat output was a little better. So must be an airlock in my system in the hoses going to the heater core since they have a hump in them. Next ill check flow to the core itself