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7/9 Updated Heater Control Valve

But it doesn't blow COMPLETELY cold, which is an issue for those of us who live in climates that need AC during the summer. The 7/9 use a blend door setup for temp control with an on/off heater valve, where the 240's use a TXV, and the 850's run a constant flow setup. Tying the valve open is an option, though it still doesn't flow as much even at wide open as the GM valve does, simply by design.

Aside from that, the GM valve seems to be made of much better plastic (never thought I'd see the day when I wrote that phrase).
 
Garyyyy, Garyyyy, Garyyy.....
Thanks! just put this in, actually Bret did, and it worked! A bit of a fuss to fit it all in but it does go and works.

:cheers:
 
I'm having issues where I'm losing a bit of coolant (having to refill the overflow tank) and then the heat gets cold when at stop lights but blows fine when moving. I think my control valve is fubared. Looks like it's been working for everyone else I'll try this and maybe it'll help.

Thanks for the write up Gary!
 
Just picked up this NAPA valve (660-1357). Still only $34.

Should be fairly obvious to the installer the the blocked port (nearest the plated actuator crank) goes TO the heater core....top line IIRC from the BB information.

Looking forward to keeping that hot water flowing thru the head at all times. Gary, yours still working AOK after 1.5 years?

Well have had this for a year now...and I'm staring down the heater core R&R on my 9 series. This NAPA valve is going in at the same time. Just got to get my T8 lighting installed in my front bay on the shop, and this task is next. Will post some pics once installed....can't wait to get some heat in the old Swede, as it was 5*F here yesterday (that's DAMN cold for the Atlanta area).
 
Today was the day! I've gutted the dash of my 940 to get the friggin' heater core out. Cleaned out the obstructions in the area of the heater core connections, and after measuring, cutting hoses, the NAPA valve is in! I"ll get my pics loaded up and add them to this post. The male ends of the NAPA valve are sure bigger than the Volvo hoses...they go on, but it's tight.

NOTE - the 94 Volvo control valve I removed was normally open (no vacuum). I've installed the NAPA control valve the same way. Without a vacuum signal from the climate control system, the coolant will be flowing thru the heater core. Vacuum on the NAPA valve will block the inlet to the heater core, and bypass the head flow back to the waterpump return pipe. As someone noted early in this thread, the control valve may be closing the flow during MAX AC. I won't know for sure until I test mine to see what conditions are actuating the valve.

Top pic shows the valve closed by vacuum signal:

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Nice clean install, looks OE:

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View showing the auto dipsticks installed, no clearance issue:

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You are correct, they do default to normally open, with vacuum closing them, same for the earlier ones, but vacuum is applied once the car is running and providing vacuum to the system. That way if you have no vacuum due to a line issue or something the default will allow for flow, and your vents will default to defrost.

Glad it's in!
 
ok so now it appears the heater core is leaking. If so this means my 93, 94, and 95 all have failed.
This one is the 94 with the Astro valve. So question; does this valve bypass the core so that if I don't use the heat, I can drive the car without doing anything else? til I get time to fix it.
 
You will still have coolant pressurizing the core, just not flowing with the Astro valve. It simply directs flow either to return to the pump or thru to the core, but even when it's 'closed' so no coolant flows to the core, the other side will still have pressure. Time to install a bypass hose...
 
You are correct, they do default to normally open, with vacuum closing them, same for the earlier ones, but vacuum is applied once the car is running and providing vacuum to the system. That way if you have no vacuum due to a line issue or something the default will allow for flow, and your vents will default to defrost.

Glad it's in!

Gary, my valve didn't actuate until I turned the AC on MAX (temp set at the bottom CLICK). The my climate control applied vacuum and it bypassed the heat core (matrix for UKers). However, when I switched the AC off, and returned to cool vent it stayed BYPASSED. Only when I shift the heat control to HOT did it remove the vacuum signal and the coolant again flowed thru the core.

It works! Putting my core back on the road this week and I'll report if any deficiencies.

Jerry, I just went to heater core hell and back....hope to GOD I never make that trip again. I'll have some pics up in my build thread soon.....what a job!
 
This is great! I recently had the plastic nipple break off and spew coolant till near overheat. Lucky I was going downhill on the highway with an exit at the bottom with a gas station there:cool:! So I just cut the motor off.. Then a quick water fill for a 1/4 mile to auto store.

I recommend to everyone to carry a 5/8 x 2" double nipple or even a piece pipe in the trunk for an easy 5 minute hose bypass. Or be stranded. I slapped another unit from a pick n pull back in, but I have the piece I purchased in the trunk with a water and a coolant jug. Till I can sort it put.

This new unit may be the way to go. I'm glad I waited to do this job now!

Nice work! Thanks.
 
After breaking the valve on my 88 765 w/B230FT while trying to replace the vacuum hose I'm looking into doing this upgrade. Was rerouting of the hoses required? After looking at the pictures and under the hood of my car the hoses on my car look like they're routed slightly different.

At the moment I have installed a plastic pipe to connect the hoses, but, this results in the coolant flowing through the heater core at all times.
 
I'm in the process of doing this upgrade. Stretching the hoses onto the valve is a bear. The hoses measure 1/2" I.D. and the nipples on the valve measure 3/4" O.D. I ended up having to put barbed hose connectors (which I already had) in both hoses and drive to NAPA to get some larger hose clamps. The original OE clamps were too small to use with the valve.

I found a nearly new GM valve that was made in Canada on a 90-95 Astro Van at the junkyard. I only had to drive 6 miles out of my way on the drive home from an appointment on Wednesday to stop at my friend's junkyard. Since my wife had the appointment I was able to wear work clothes. She really didn't seem to mind waiting in the car.
 
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