99 Ranger 2.5 - No heat-What next???

[Leigh]

99 Ranger bought used, so no history.

AC/ blower works, but no heat. With heater on "Full' there is absolutely no evidence of warm air, & since AC compressor continues to be engaged, the air actually feels cooler than outside ambient.
Trouble shooting so far:
(1) Upper radiator hose relatively hot/ Temp gauge mid-way/Normal suggesting thermostat, & Water-pump OK.

(2) Inboard heater hose (Inlet, I assume) is hot either side of 4-way control valve.
Outboard heater hose is only barely warm at outlet from heater core.
I flushed the Heater core until running clear in both directions, but made no difference.

(3) The 4-way Heater control valve has the AC Vacuum line disconnected, but it's my understanding that this shuts hot coolant flow to the core with Max AC On.
It's spring loaded in the Open position, so shouldn't effect heater ops.

(4) I removed the Blend Door motor, and checked that it operates OK.
The motor shaft, and the receptacle it engages with show no signs of damage, or distortion.
I'm not sure how to positively confirm that the Blend door is working properly, as I can't see it, but, from what I've read on the matter, the results of the steps I've performed indicate that the Blend door is OK.

I'm not sure where to go next with this? I could try replacing the Control Valve, but I hate to throw parts/money at the problem without a reasonable conclusion of what the cause is.

Any help/suggestions would be most appreciated.

LW

 

[mp3deviant721]

Did you check your coolant level? Low coolant level can cause no heat, I worked on a Taurus that had a similar issue. Also make sure your coolant is in good shape, dirty coolant can clog up the heater core. Actually, now that I think about it, that car had both of those issues. After a coolant flush and cleaning out the heater core, the car had great heat.

 

[AgPete139]

Sounds tricky.

I used to not get heat, until I replaced that spring-loaded valve in the engine compartment. I don't have much need for heat here in Texas.

I'm surprised that you are getting no signs of heat at all though. Is the blower at least blowing and working at all? If all lines are open, and the blend door is unobstructed, you should be getting heat through your heater core that has been flow-tested. When you manually press back the heater valve, does that change the temperature (by feel) of the hoses?

I would seriously take this off and check it, since it's a wear item and goes out. The only reason I suggest this is because it sounds like you have covered all of the other bases.

 

[Earl43P]

If your vacuum system is working properly, you should have enough residual vacuum remaining after the engine is shut off to turn the key to Run (dash warning lights on) and move the heater temp knob and HEAR the blend door operate fully in both directions. I'd have the glovebox popped fully open to listen for that.

I have a similar problem.

I have a new 4 way valve waiting to be installed. It was about $20.

The previous owner of this truck obviously had this problem because he bored holes in the plenum so he could SEE the blend door move (which mine does). I stuffed a rag in the hole, closed the glovebox back up and forgot about it until i read your thread.

It may be a week or so until I replace my 4 way valve, but I'll let you know if my heat output increases when done. (I am subscribed to your thread, so I'll "be back")

 

[RangerRyan]

I had the same thing but the next week my water pump went bye bye. But your water pump is fine.

 

[Leigh]

Thanks for the replies----And----

Thanks for the replies, guys.

As I stated, the Blend Door Motor is removed, the shaft has no defects, and it turns properly with the Temp Control; plus there is no deformation of the Blend Door Receptacle that mates with the shaft, so I assume the Blend door was/is working properly.

The fact that the heater outlet hose is barely warm, though the core was flushed & flowed clear in both directions, would seem to indicate a "restriction", or flow re-direction at the 4-way valve???

There is a 1/4" ID "fluid" line that "T"s into the Inlet hose between the 4-Way valve, and the Heater core inlet, which I'm not sure of it's function---- Possibly to a Temp sensor--- but, if so, what does it control???

As to the vacuum line on the 4-way valve's AC Shut-off valve; it would have to connect to a specific vacuum outlet that is actuated by the AC Control when in MAX; but I don't have a clue where that outlet is located?

So many mysteries--So little time

Leigh

 

[brinker88]

Its prob that vacuum valve by the firewall with the 4 hoses on it coming/going from the heater core. I just fixed my dads. I eliminated that valve with a brass ball valve and a union

Simple fix.

 

[Earl43P]

Update on mine = fixed.

Replaced that 4 port valve and flushed brown coolant out of the heater core.

The rest of the coolant is/was bright green.

The valve was definitely not flowing any coolant into the core.

I now have mega-heat, and the new valve does actuate in Max AC. But I have to rev the engine to make it stroke. I'll call that normal until convinced otherwise.


Leigh, you need to find the grey vacuum line for that valve. Mine routes under and outboard of the AC filter/dryer.

 

[tazzryan]

Its the heater core clogged or the temprature control valve, 0r the thermastat ckeck those items. LET THERE BE HEAT!!!!!!
HAAA!! HAAA!!

LOL!!!!!

 

[joemac]

I'm fighting a very similar problem. I'd bet it is in your blend door. Both my heater hoses are scalding hot, actuator motor is working, but I turned my blend door manually a few times, turned on the truck and got heat with the actuator still out. The last owner pulled the heater valve before hand so I know that's not an issue.