Hi, needing some advice on this heater issue I'm having. I've done some research on it, but wanted to get other opinions on what might be the problem. I have a 98 Ford Ranger 2.5L and my heater only blows cool air, here are the symptoms:

-Engine does get hot to the normal point.
-Coolant level is within standards.
-Only the right side hose (standing in front of the truck) gets hot.
-There's no vacuum to the heat valve while on heat (suppose to be?).
-The fan blows.

I found the vacuum line was broken to the heater valve yesterday and replaced it hoping it would fix the issue, but it didn't.

I've read a lot about the blend door, so I'm really hoping it's not that. If I manually open the heat valve, the other hose does get warm also. I was thinking blocked core? Thanks in advance.

Have you tried holding the valve open manually to see if the hose gets warm downstream of the valve?

I have. It does get warm, but I couldn't hold it open long enough for it to get very hot.

Pin it open with something, turn the fan on inside and see if it gets warm.

Ok, I used a piece of plastic tubing to hold it open. The hose did get warm (not exactly hot), but the cab air seems to still be ice cold. The engine temp was warmed up also.

Is the system full of coolant?

Yes. The coolant isn't as green as it should be though, which is why I thought possible blockage.

I apoligize - I see where you have already done the hose stuff. Not that should fix anything but have you noted the position of the valve when you turn the on in the cab then when you turn it off?

And... I'm wondering if the thermostat is staying open a bit and not letting the engine warm up all the way...

And could the blend door be tested in ac mode?

Not sure I make the connection between color and blockage - ?

When I turn on the heater, the valve doesn't move, there's no vacuum coming from the line attached to the top of it.

The engine temp gets to the half way point between H and C.

I'll check if the AC works during lunch.

The color- I was wondering if it's been stagnant or something causing a discoloration, I'm not sure what to think of it...it probably hasn't been flushed in a long time.

Well... You need to fix the vacuum thing or the rest is pointless. And I'm thinking if you fix that it may resolve the door issue if there is one because if there is a line open there may not be enough vacuum in the lines (if connected) to pull the door to the correct position...

You're probably seeing 'antifreeze green' aka normal color, not stagnant water, etc. But always good to flush if you haven't in a while...

Ok, I'll find the schematics & see if I can trace the leak. Thanks for the help!

nopwbc was nice enough to send me a trouble shooting guide. It points to the water pump impeller. I found some literature that said the vacuum should only be applied during max ac and Off modes, which I found to be true when I tested it. Both hoses don't get hot at any point but the engine temp reaches normal; I'm going to brave replacing the water pump in hopes it solves the problem. Thought I'd post the below for anyone else that had confusion with this...See below regarding the literature:

OFF
Vacuum is applied to inlet duct door, preventing outside air from entering system. Heater water control valve is at full vacuum, preventing hot coolant from reaching heater core. Vacuum is applied to floor/panel and panel/defrost door actuators. Blower motor and compressor will not operate in this mode.
MAX A/C
A/C compressor operates in this mode. Vacuum is applied to air inlet door, preventing outside air from entering system. Heater water control valve is at full vacuum, preventing hot coolant from reaching heater core. Vacuum is applied to floor/panel and panel/defrost door actuators. Airflow exits from panel vents. Blower motor is on.
A/C
A/C compressor operates in this mode. Vacuum is not applied to air inlet door, allowing outside air into system. Heater water control valve is at no vacuum, allowing hot coolant to reach heater core. Vacuum is applied to floor/panel and panel/defrost door actuators. Airflow exits from panel vents. Temperature setting can be changed manually. Blower motor is on.
Vent
Vacuum is not applied to air inlet door, allowing outside air into system. Vacuum is not applied to floor/panel door actuator. Vacuum is applied to panel/defrost door actuator. Airflow exits from panel vents. Temperature can be adjusted manually.
Floor/Panel
Vacuum is not applied to air inlet door, allowing outside air into system. Heater water control valve is at no vacuum, allowing hot coolant to reach heater core. Partial vacuum is applied to floor/panel door actuator allowing door to open partially. Vacuum is applied to panel/defrost door actuator. Airflow exits from panel vents. The A/C compressor operates in this mode.
Floor
Vacuum is not applied to air inlet door, allowing outside air into system. Heater water control valve is at no vacuum, allowing hot coolant to reach heater core. Vacuum is applied to floor/panel door actuator. Vacuum is not applied to panel/defrost door actuator. Airflow exits from floor ducts.
Floor/Defrost
Vacuum is not applied to air inlet door, allowing outside air into system. Heater water control valve is at no vacuum, allowing hot coolant to reach heater core. Partial vacuum is applied to floor/panel door actuator. Vacuum is not applied to panel/defrost door actuator. A/C compressor operates to dehumidify air and reduce windshield fogging. Airflow exits from panel vents and floor ducts.
Defrost
Vacuum is not applied to air inlet door, allowing outside air into system. Heater water control valve is at no vacuum, allowing hot coolant to reach heater core. No vacuum is applied to floor/panel door actuator or to panel/defrost door actuator. A/C compressor operates to dehumidify air and reduce windshield fogging. Airflow exits from defrost outlets.

Sounds like a plan, let us know how it goes -

Update: I did some more troubleshooting before deciding to plunge into something time consuming. I found the hose from the water pump to the valve was hot, as well as the hose from the valve to the firewall; however, the hose from the firewall back to the valve (from the core) was not hot. I went ahead and replaced the thermostat, just to do it, and took apart the valve and tested it. Both were good, so I tried blowing through the firewall hoses and I couldn't.
I put a waterhose to one of the lines and flushed a lot of junk out of the core. I did this back and forth on both lines until the water ran clear and there wasn't as much resistance. After putting everything back together and refilling the antifreeze, it was working again! The core likely needs replaced, but hopefully this will get me through the winter. And I have to say, it was extremely nice having a heater this morning. Hope this helps someone!

Thanks for everyone's help!

Thanks for posting how you fixed it - I think my core has been leaking for a while but i understand its a major job to get it out so I have been putting it off. Now that I have it down for an engine replacement I may replace the heater core...