Ok guys and gals, this one has me STUMPED. Hopefully I have the correct board for this because I don’t see an HVAC specific board. I have a 2000 Ranger 2.5L 2WD. The truck puts out almost NO heat (temperature wise, fan blows strong) while MOVING, but if I’m sitting in a parking lot, the heat SLOWLY comes back. It’s NOT an engine RPM thing because holding the RPM at 1,200-2,000RPM will ACCELERATE the rate at which the heat returns. I have disconnected the vacuum hose to the bypass valve, no fix. I have disconnected the A/C high pressure safety switch in order to switch to Max A/C and close the recirculation door, no fix. No air in the system either. I actually disconnected the small hose off the inlet hose to the heater core that goes to the EGR cooler in the intake manifold to be sure all the air is bled. I am COMPLETELY stumped AND FREEZING while I’m going down the road! If it was a plugged heater core, my thoughts would be that revving the engine sitting would duplicate the problem, NOT help it! The truck has a BRAND NEW thermostat and the ENGINE TEMP is completely steady just below half on the gauge. New radiator car as well. Those were both changed in an attempt to fix the issue. Problem remained unchanged. This SEEMS to be something related to forward motion into the air that is super cooling something. The colder it is outside, the worse the problem is! Has ANYONE experienced the same issue and can offer me some insight as to what to do to fix it? While sitting, it will RUN ME OUT of the truck it gets so hot! Drive down the road and I freeze my baguettes off!

 

Clogged / blocked - up heater core would be my first guess.

 

+1 ^^^

That's what it reads like

Does the dash Temp gauge stay steady after warm up and driving?
So its not an engine thermostat issue, long shot

After heater goes cold, pull over and pop the hood, feel BOTH heater hoses at the firewall, both should be HOT, if not then there is poor flow thru heater core

In 2000 Ranger, Cab Temp **** controls an electric Blend Door actuator
When engine is warmed up and you are Stopped, so have heat, turn the **** to COLD and air should get cold, if not then Blend door is not working, so could be moving when driving and cutting off the heat


Flush the heater core
Cold engine, parked outside
Remove both heater core hoses in engine bay, but at the By-pass end of both hoses
Bend either hose down to point at the ground
Hold running garden hose on the other hose end, to flush out the heater core, then REVERSE the hoses to back flush it the other way

You can blow out the heater core, using your lungs
Then pour HOT water with CLR or Vinegar(not both) mixed in, into the core
Wait 20 min then Flush it out
Repeat as you see fit

On a 2000 Ranger, you pretty much need to pull out the whole dash to replace heater core, so hopefully flush will work

Also on any vehicle you should reverse heater hoses at the firewall every 2 years or so to reverse the flow thru the heater core, this helps keep it cleaner so it can last a few years more

 

2000 Ranger has a CABLE operated blend door, at least mine does. I can feel the cable move and hear the door moving. But it ended up being a faulty heater control valve. Even with the valve unhooked from vacuum, it would actually prevent hot coolant from reaching the coolant temp sensors it was blocking the coolant flow so badly. I completely DELETED the HCV and it works PERFECTLY now.

 

No, it doesn't have a cable operated blend door unless someone changed the panel to this type:http://img.justparts.com/eImage/0471...80811488ba.JPG
The slider panels used cables, 1994 and earlier

The 1995 and up used *****, like this: https://i.ebayimg.com/thumbs/images/...M1n/s-l300.jpg
This means electric blend door

So easy to tell what you have just by the control panel

Glad you got your heat back, thanks for updating the thread and THE FIX

 

For the longest time, the temperature would remain steady on the dash temp gauge until 2 days ago when all hell broke loose. Coldest day of this fall/winter so far here in Ohio and I suddenly lost even the little bit of heat I did have and then the temperature gauge started going all funky. So, it seemed to me to be air in the system so I replaced the radiator cap AGAIN that was just replaced in August, this time with a standard cap rather than the ventable one I installed in August. No fix. Replaced the thermostat AGAIN, found the gasket had become un-bonded and saw the little welds that weren’t filed down flush so I thought coolant was bypassing the thermostat because the seal was no good. Still no fix. At this point I don’t even have the heat at idle that I used to have and it was IMPOSSIBLE to get the temperature gauge to climb to where it used to sit and would most of the time be buried full cold. When I replaced the thermostat, I paid extra attention this time to how the coolant flows through the thermostat housing. I originally thought it was a poor design from Ford and when the thermostat would close, i.e. getting up to highway speeds on a cold day and the temperature would drop, the hot coolant was cut off from the heater core inlet hose, but that didn’t even make sense since that would also cut off the coolant flow over the temp sensors. So, this time I noticed the bypass port around the thermostat for the heater core and temp sensors. That’s when I realized that if the HCV was plugged or otherwise malfunctioning, it would ALSO cut off coolant flow over the temp sensors. That’s when my attention focused on the HCV. A plugged heater core made ZERO sense because before I could sit there in park and rev the engine to 2k and it would bring the temperature up as well as restore heat to the point where I was turning the temperature down. The HCV was already suspect which is why I had the vacuum line to it disconnected and plugged to not get a vacuum leak since vacuum CLOSES the valve and shuts off coolant flow to the heater core. But even that really didn’t make any sense because engine RPM is engine RPM, load or no load, the water pump is spinning the same speed which is why it was baffling me that this was ONLY happening while in motion. Then, when I lost my temperature readings as well, I did a little Google search for HCV symptoms and found that my truck was exhibiting ALL symptoms other than the valve leaking: Erratic/low/no temp readings, loss of heat, etc. which is when I went and purchased 2 5/8” hose couplers and deleted the HCV altogether since I knew there was still a blend door to control my cabin temperature. VOILA! It worked. I actually had gotten to the point where I had disconnected the A/C high pressure safety switch to keep the compressor from engaging to allow me to turn to “Max A/C” and close the fresh air door to try to build up more heat in the cab. Well, NOW with the HCV gone, I can turn the heat 2/3 of the way DOWN (pointed to the blue area where the red stripe just starts) AND have it on standard vent with the fresh air door OPEN and I am at the PERFECT temperature. If I go to Max A/C and have the temperature **** all the way hot, I’ll die of heat stroke now! Why do they even have that valve in there if the system works just fine with it completely removed? I can still cut the heat off completely by going to full cold using the blend door. It just doesn’t make any sense why they would complicate the system with that valve when everything works just fine without it, unless it’s going to cause issues when I use my A/C in the summer now. If it does, I’ll drop the $25 on a new HCV at that time and hook up the vacuum line again. Now, I know SOME vehicles actually use that valve as the sole temperature control method. Honda Pilots are that way. The Temperature “Blend Door” Actuator actually moves a cable that opens and closes the HCV on that vehicle, but that design is a bit strange because there is a delay when you turn down the temperature since it still has to bleed off the heat from the coolant that is in the heater core before the temperature actually drops. It might get hot right away from the hot coolant suddenly rushing into the heater core, but when you want it cooler, there will be a definite delay. IMO, an HCV is just an over complicated method of controlling the temperature when a simple blend door does just fine!

 

No, it DEFINITELY has a CABLE operated blend door with a **** style climate control panel. You can feel the tension in the cable when you move the **** and there is that distinctive “clunk” when you move full hot or cold and the blend door actually hits the end of its travel. Electronic actuators move slowly and will never hit the end of the travel at the same time you hit the end of the ****/lever travel unless you very slowly move the ****/lever. This system is RIGHT NOW. There is NO WAY that is an electronic system. There is too much resistance in moving the **** quickly for it to be a simple rheostat that sends a signal to a climate control module which in turn moves an electronic actuator. It ALSO has the vacuum operated mode selector because you can HEAR the hiss when you change settings with the engine off. I think I might have a vacuum leak or a faulty “black ball” vacuum reservoir under the hood because when you’re at high throttle settings like climbing a hill and manifold vacuum decreases (manifold pressure increases), the air stops coming out of the vents until you back off the throttle and restore vacuum to the system. The ONLY thing electronic about it is the fan speed control. Maybe the 2001 when they changed body styles slightly went to electronic controls, but the 2000, at least the 4-cylinder XLT models, still have cable/vacuum operated climate control systems.

 

ok, now even I’m confused because I just looked up the parts for the system and it does look to be electronic. Unless my truck is different. But that HAS to be a cable operated system in my truck