heat valve...

slabelle67 · Dec 26, 2006

i have the 1989 cherokee laredo and was wondering if it is suppose to have the heater valve. it doesn't have one at the moment. it does have the pink vaccum line coming out of the firewall. would like to know and get a diagram if anyone has one...thanks

Saudade · Dec 26, 2006

Yes. It normally has a heater valve. It's vacuum operated and merely allows coolant to flow through the core. If it's been bypassed and the vac line is plugged, there's not real issue other than your core is hot when you don't need heat. The blend doors still keep the hot air from circulating in the cabin.

Here's a pic of my '88.

slabelle67 · Dec 26, 2006

hey thanks alot for the pic. also when control is in heater position nothing comes out on the floor. vents and defrost work but not the floor. can hear it blowing etc. but also feal cold draft. maybe ducting is off? trying to get an idea before tearing into the whole dash.

Blaine B. · Dec 26, 2006

You don't need a heater valve, technically. You can plumb directly to the heater core, making sure to plug the vacuum line intended for the heater valve.

Most newer vehicles (including Cherokees 97+) do not have a heater valve.

Matthew Currie · Dec 26, 2006

Check the fresh air door at the bottom right (if your vehicle has AC). When you turn the heat control all the way to "off" that opens. If it's open or leaking, you'll get cold air no matter what. On non-AC vehicles, that door is not present.

Saudade · Dec 26, 2006

Are you saying it only blows out of the defrost vents? Does it blow hot (after you get to full temp)?

Blaine B. · Dec 27, 2006

The vent on the floor (you can see the blow fan behind it) opens when in MAX A/C mode.

Jess · Dec 27, 2006

Blaine B. said:
You don't need a heater valve, technically. You can plumb directly to the heater core, making sure to plug the vacuum line intended for the heater valve.

Most newer vehicles (including Cherokees 97+) do not have a heater valve.

x2...don't need the valve, it has no control of which vent blows

slabelle67 · Dec 27, 2006

seems eveything works the way it should except that when on heat it wont blow through the vents on the floor. i can hear it blowing in behind the dash some where but on the floor where it should. on top of that i can feel a draft of cool air coming from some where on the passenger side. looks as the door directly to the blower is closed. just bought the rig and some one has messed with it and i am trying to get a visual on putting things back the right way. thanks for eveyones input. very much appreciated

UN-limited'89 · Jan 17, 2007

hi there, i have a '89 limited with a similar problem, 5-90 gave me some input and it was very helpfull.
my question is that is if the hose that goes to the water pump is conected to the thermostat out put and vicevirsa, would this affect in any matter the heating process?
thanks

Blaine B. · Jan 17, 2007

That would backflow through the heater core, possible loosening up gunk and contaminating your entire cooling system.....plus if you backflush heater cores, they can spring a leak....

I think it would heat the same though, given everything else was fine.

heat valve...

slabelle67

NAXJA Forum User

Saudade

NAXJA Member

slabelle67

NAXJA Forum User

Blaine B.

NAXJA Forum User

Matthew Currie

NAXJA Member #760

Saudade

NAXJA Member

Blaine B.

NAXJA Forum User

Jess

NAXJA Forum User

slabelle67

NAXJA Forum User

UN-limited'89

NAXJA Forum User

Blaine B.

NAXJA Forum User

Similar threads