Hey guys,

I am kind of a gearhead, so if I don't use the right terms or describe something the right way, then bear with me, please.

I have a 1998 Ford Ranger 4-cylinder.

It happened maybe a month or two ago when all of a sudden my heat in the Ranger got lukewarm. The heat always used to be really hot. The blower fan was on level 4 when it happened. I noticed that the engine heat gauge needle started to go up and down, the heat then just became lukewarm on blower level 4 if you put your foot on the accelerator.

My neighbor who manages a bodyshop and who works on cars ALL the time replaced the thermostat, etc, and flushed/bleed the radiator twice.

The heat on blower level 4 didn't get any warmer.

But what I have noticed is that if I have the blower level on 3, the heat is HOT like it used to be. I don't know why the heat won't work on 4, but is really hot like it used to be on blower level 3.

Anyone know what the problem could be?

Thanks!

 

It MIGHT be an issue with the heater blower resistor. My friends F150 had a similar issue where the first 2 settings on the controls didnt work, but the last 2 did. Replaced the resistor and everything was fine.

 

Have you checked the actual water temperature ?

Maybe the temp level switch is bad and won't let enough warm water to the heater.
Won't know until you see if the water is really hot to not !

There might be a way to check the temp level switch, I don't know !

 

check your heater control valve its on the intake side of the heater core it opens when you switch it to hot and its vacuum controlled so then line may be lose or broken valve and they are pretty cheap to replace mine started leaking pretty bad and i had similar issues but it could also just not be opening all the way.

 

Reads like heater by-pass valve or the heater core is partially blocked.

Flushing just puts more junk in the heater core.

You need to Back Flush heater core, flow water backwards thru the core and push out any debris the way it came in.

Google: back flush heater core

Model doesn't matter they are all back flushed the same way

When flow thru the core is reduced and you increase the blower speed the hot air gets cooler because heater core can't replace the heat as fast as you are taking it.

This blockage can also cause temp gauge to go up and down when heater is being used, assuming there is a by-pass valve.