Heating Problem
 

In my 2000 2.5L I'm having little to no heat. Let me tell you everything I possibly can. When I have any vent setting (either floor, top vents, or both) I can drive with barely any heat. If I'm going up a hill the temperature of the air coming from the vents goes up but the top temperature I feel is around 65-70 degrees. This is while the temp gauge is reading normal. Now at cruising speeds the temperature will drop all the way down to the lowest setting. It will go right back up when I turn the knob to OFF or Max A/C (heater control valve closes, 4 port BTW).

Thinks I've checked:
Heater Valve works correctly (by looking at the rod move, under vacuum and without)
Heater Inlet hose is hot, heater outlet hose is lukewarm.
I flushed the heater core itself, backwards, forwards, backwards, forwards, and again backwards.
(one hose in bucket other connected to 5/8" barbed hose adapter connected to pistol style sprayer)
The flow doesn't seem too constricted.
After doing this I filled the heater the best I could with coolant. Parked on a 35-40 degree hill making the radiator cap the highest point in the system and ran the truck for about 10 mins with the cap off.
Still same results, actually a little worse than before the flush.

Could this still be caused by a clogged heater core? If so, is there a chemical I could pour into the core to dissolve whats plugged in there? Already used water hose, afraid to use a higher pressure air hose.

Have you looked at your thermostat? New one is cheap to try. If it is stuck open, that'd explain why temp would go down while cruising at speed. As well as when you give it gas and engine temp increases.

If the inlet is hot and the outlet is lukewarm, I would suspect that the heatercore is plugged or is having an issue transmitting heat (pull the cover inside the cab under the dash just to see, make sure that there's no build up of dirt or dust in there blocking the flow of warm air - should only be four screws and 10 min if they're like the older Rangers). Assuming that your valves are all working properly, then it might possibly be a thermostat issue but if it hasn't been change for a while its just cheap insurance anyways to change it anyways to avoid problems down the road. LR

Pull off your heater hoses at the firewall and check the heater core for gunk.Flush out the core with a hose if need be.This is a good easy first step.

I"ll go with Corey on this as I've had the same happen with a stat stuck open.

To get to the heater core on models past like 1995 you have to remove the dash. I've replaced one in my buddies 2000 (same as mine), and I had to pull the dash.

Already flushed the core, mentioned in OP.

I've replaced the thermostat twice, once a whole year ago( replacing original), and again 6 months ago. Both times stuck open. I've replaced them with Murray brand. I went ahead months ago and bought a Motorcraft thermostat. I'm thinking that the Murray brand is crap. I'll replace the Murray with that Motorcraft when I get a chance (might as well flush the crap out of the whole system). I'll let you guys know.

Well I flushed the system out using that Prestone Flush Kit. Then I added the Prestone Flush chem to it and ran it. (all this without the thermostat in it). Put new thermostat in......same problem. Looks like its the heater core. Dang is it cooooold outside. Good thing its warming up this weekend (3 day weekend). I may tackle the new blend door for the EATC and new wiring harness for Power doors.

Some little info I though I would share about the thermostat housing (2.5 L):
Behind the thermostat is the hole for the coolant to pass by the sensors and into the heater control valve. In other words there is always coolant flowing through this passage, no matter what the thermostat is doing. It would make sense that it was my heater core being clogged because if the valve is open and fluid isn't flowing because it is clogged it would cause the temp gauge to read low because this would stop the flow of coolant through this part of the system. When I turn the heat to OFF it closes the valve bypassing the heater core (having better flow) so fresh coolant would flow over the sensors causing the temperature to climb back up to normal.

I just replaced the heater cored and filled up the coolant. But now its heating (pretty good heat but not REALLY HOT) and then again at cruising speeds the temp drops. I felt the heater hoses.....inlet is too hot to handle, the outlet is like lukewarm. Could it just need to have the air bleed out later, possible air pocket?

If you have one, I would recommend removing the vacuum actuated valve that is on the heater core inlet hose. These things fail more often than not, and restrict flow into the heater core. If you decide to remove it, a simple solution for the extra vacuum hose is to cut it so you have an open end, then melt the hose and pinch it shut.

Here's what it looks like. You can buy a coupler at any parts store to retain the stock hoses. Just make sure to pick up two clamps while you're at it.

Attachment 91040

I actually took the heater valve off and ran it as part of a test. Since mine was a four port valve, I replaced it with two 5/8"couplers.

Update: After Disconnecting the heater hoses and trying to get all the air out It seems 1000x better. There is still a temp gauge change every now and then from right in the middle to down about 5 degrees of rotation colder. I'm sure there is still more air to get out.

Can you buy bleeder valves to install in the heater hose lines?

After melting a hole in my heater hose the other day from it touching the EGR supply tube, I am having the same problem with a lack of heat now. I'm assuming I've got an air pocket in the heater coil as well. I've never had to remove air from the coolant system....what method did you use?

Since the highest point in the system is the heater hoses where it connects to the heater core, I took off one line and filled it with coolant until coolant started flowing out the nipple of the heater core (make sure there isn't any vacuum on the heater control valve, you can just unplug the gray vacuum line).

It also helps that I have the Prestone flush kit installed on the hoses. I can just hold the hose up and unscrew the cap and top the coolant off. Thats about the best way to get the air out.

Very good thread. Also having heat problems. Slightly warm heat but not even close to where it should be. Thanks for all of the good suggestions! (2006 Ranger)

Is the blend door moving properly? If it is sticking or not moving to close off the cold air you will never get good heat. The vacuum control just opens or closes. The temp of the heat is controlled by the blend door.

The blend door was not moving at all. Had to replace the unit. Took it to a local mechanic, that was a little too much for me to accomplish. Thanks enjr4!

1996 ford ranger 2.3
 

Hey guys I'm new too this site. But just bought a 1996 Ford ranger 2.3 5 speed to drive back and forth for work. Everything is great becides I see the temp gauge go from the middle to a little over half way. I have replaced the t- Sat, radiator cap, new radiator, new water pump. New heater core. So I'm kinda lose for words to why it's doing it. I know the t-sat was for 192 degrees. Anything else y'all can think of? Oh yea and I really only see it at high rpms when shifting.

Can someone explain how the thermostat would be affecting the heater? I thought the thermostat is for the cooling of the engine. I have a 2011 Ranger XLT 2.3 5-speed manual and have no heat. 91,000 miles. Had the cooling system flushed 10,000 miles ago. Heater blows only cold air whether on AC or Heat. Haven't noticed any leaks or odors inside the cab. I thought about replacing the thermostat but the auto parts salesman said it wouldn't affect the heater, but only the engine temperature. I thought replacing the thermostat might be a good first step and if that didn't work, a flush of the heater core would be second.

Just a bit more information about my heating issue. I just started the Ranger and let it idle until hit reached operating temperature. With the heater set on High speed and temperature, I raised the hood and felt both inlet and outlet hoses of the heater core. Both were warm. I was expecting the outlet hose to be cold if I was having a clogged heater core issue. Thoughts?

Heater valve question
 

I don't get any heat and air only blows through my dash vents, but not even a full flow of air. A while ago the vacuum line on my heater valve broke and then the heater hose itself went to shit so I tossed the hose (including the valve) and ordered a new one to replace it. I'm realizing now that I need to know which heater hose is the inlet and which one is the outlet to the heater core. I have a 98 v6 3.0 4x4 and it also has had some vacuum issues and I figure that's why I can't get the air to blow anywhere else. So I have a few questions:

1) Which heater hose does the heater valve go on (it's the 2 port no the 4 port), the inlet or outlet?
2) When installed, which way does the valve face? Does the vacuum port face the front of the truck or face the firewall?
3) Which heater hose is the inlet and which is the outlet according to me standing at the front of my truck looking at the engine
4) What should be my process for determining where the vacuum leak is coming from?

I've tried searching for every type of question regarding the issue and watching a ton of videos but I can't find any info that shows me where things are on my year make and model truck. Photos would be sooo helpful

Thanks