Lack of strong heat UPDATE

[Russkcpa]

1972 Tii

Thanks to Brandon-Buscuit-Mike for their previous suggestions

Here's the good news:

When I move the temp from cold to hot the cable functions on the heater control valve AND the cold air mixer door DOES close. So NO broken cables.

Here's the bad news:

Heat is on a scale of 1-10 about a 6

My 1976 2002 is a solid 10 so I know the '72 still has issues

I DID notice small dripping from the heater control valve (I think only when the control was on cold and the valve closed) I'm wondering if MY NEXT step is to replace the heater control valve OR back flush the system

Also-as a side note-heater and defrost controls are all screwed up. (for example-if heater is off and defrost is 1/2 way I get almost full blowing on floor)Is that an easy adjustment ?

Thanks

Russ

[BillWilliams]

There are probably easier ways, but here is what I do to check the valve.

I take the hose going from the heater valve to the block away from the heater control valve, pull it out of the firewall, and either with a flashlight or a screwdriver, look or feel into the heater control valve and have someone open and close the valve.

This allow you to really determine if the cables are openening and closing the valve completely.

As far as the cables go, I do not have a real good suggestion other than look under the dash with a good flashlight, operate the cables and see what is causing the defroster to open when you open the heater flaps.

As you know, anytime you mess with anything around the control valve, you chance breaking the plastic tab from the heater box. Many 02s already have broken tabs. No worry though, the heater controls seem to work fine even with broken tabs.

If the valve is working ok, it may be time to remove the heater box and rehab it following the great FAQ on this site. Having the heater core checked and boiled by a radiator shop is important step in that procedure.

There are previous posts on rebuilding the valve and several vendors waiting to take your money for a new valve if your valve is leaking beyond repair.

[ingraham]

1. Take off the other hose as well, and flush out the heater core, first from the left (non-valve) side, then from the right (valve) side with a garden hose.

2. Heater control primer: Your heater has four controls:

a. Temperature

b. Fan speed

c. Floor air flow

d. Windshield air flow

For a given fan speed, the floor air flow slider should provide more or less air out the sides of the heater box independent of any other control. Likewise, the windshield air flow slider should control defrost flow independent of the other controls. To check, turn the fan to high, shut off the floor air, then feel the air coming from the defroster vent while moving the windshield slider. Then shut off the windshield air, and feel the air coming from the floor vent while moving the floor slider.