Heater Woes, Wife and Kids Freezing! Please help!

[stevebrum1975]

Im a father of Four! Money is hard to come by! LOL! So Ive been working on this myself! Enough Said!
99 DODGE DURANGO
OK! Heres the deal! My heater will not blow hot air. It seams that all the flaps inside the airflow chambers are working or at least we can hear them switching over when we change them. Checked the vacume lines to be sure...seam to be all ok! Replaced the Thermostat, Flushed the heat hoses and back flushed the heat hoses. Flushed the whole system. The flush was clean water about 55lbs of pressure. Both flushes seamed to freely flow! Still no heat! Car runs about 200 degrees! I feel like that may be just a tad hot but not overly hot!

Here is what i cant get my head around! Remember, Water flowed well with the flush (Back and Forward).... But neither of my heater hoses to and fro the heater core gets hot! Logic tells me that NO HOT WATER TO THE CORE.... then NO HOT AIR BLOWING THROUGH! Whats the deal? If the pump isnt working then the car would run hot...Correct? Lastly, the A/C is not charged or vaccumed...Would this have ANYTHING at all to do with it! I replaced the AC compressor just before winter! Havent had it charged because , well, $$$$$ and its cold outside! LOL!

Please help!
Frozen in Nashville!

[grd4aces]

Are you sure that the thermostat you changed is working? If the heater hoses aren't getting hot, it's usually the thermostat or the fluid level is low. Check the level in the radiator, not the the overflow, but wait until it is cool enough to open safely.

[MagicRat]

Many cars have a heater core control valve. This is placed somewhere along the heater hose and directs hot coolant into the heater core only when the ventilation controls are set to warm up the interior.

If no heat is required or if the air cond. is on, the valve shuts off coolant flow, to keep the interior cooler and make the truck's radiator work more efficiently.

Typically these valves are vacuum controlled. If the valve is jammed or the vacuum line is disconnected, you may not be getting any flow.

Try to find this valve and free it up, or remove it altogether.
In the past, I have replaced the valve with an in-line brass ball valve (like a faucet) that is intended for home plumbing systems. I have soldered on short 1/2 inch or 5/8 inch copper pipe on each end and placed the heater hoses over it. Then I simply shut it off in the spring and open it again in the fall.

(Many older heavy trucks use this system)

[angus10]

Try jacking the front up as high as you can get it, remove the radiator cap, turn heat to hot and start motor. Let it run until it gets up to temp and the Tstat opens. Add coolant as needed to the radiator. This will get rid of any air bubble that might be in the heater core, and eliminate that as a problem anyway. The water pump could be at fault, it can pump enough coolant to keep the motor at good temp, but not circulate it at full pressure to the rest of the system. Also try moving the heat control switch rapidly to full hot and make sure you hear it slap against the box to seal.

And lastly, you are wrecking your new ac compressor by not having it charged. Even in the winter,when you have the defroster on, it is designed to cycle on and off every so often, to not only help with condensation on the windshield, but to keep the refrigerant oil cycling throughout the system to keep the seals and such from drying out.

[mzdeal]

Based upon my '99 D shop manual, the heater loop is an open loop. That means hot coolant should flow through the heater hoses at all times, and it bypasses the radiator & thermostat (a separate loop to and from the pump).

So if the heater hoses don't heat up at all, AND you're also pushing hot stuff through the radiator (feel the radiator out hose) then you have a blockage in the heater loop. Check this out by pulling off the heater hoses and seeing where there is/isn't flow. Worst case is you need a new heater core. Find the blockage and remove it.
The pneumatics here only operate air routing doors and not any coolant valves ('99)

Manual diagnostic checks are these:
- Coolant level low (inadequate heating)
- Obstructions in heater/hose fittings
- Heater hose kinked
- Water pump not pumping to/through the heater core

For obstructed coolant flow:
- Faulty water pump
- Faulty T-stat (stuck open)
- Pinched/kinked heater hoses
- Improper heater hose routing
- Plugged heater hoses or supply/return ports
- Plugged heater core

This assumes you are correct in that the heater hoses do not get hot.
If you goofed on that, it could be a flapper door in the air path.