User 52121

So I noticed my A/C doesn't work anywhere near as well as it used to. It's fully charged (R-12 yee-haw!) but I'm not getting much more than 60 degrees out of the vents.

All the clips are good, the mix valve moves when I adjust the **** (and if I disconnect the mix valve and manually open the mix flap all the way I get HEAT) so it's doing its job.

I noticed that the heater control valve doesn't seem to be moving at all when I peek down there. It's my understanding that there is a vacuum solenoid under the dash (passenger side) that kicks on to suck that valve closed. Is that correct?

It seems the lever arm on the valve is "springy". Pushing the valve *against* the spring *closes* the valve, right?

Should I expect that with temp controls set to "full cold" that the HCV would pull itself *against* the spring?

Just want to be sure I have my understanding correct before I troubleshoot further tomorrow afternoon. I'm thinking I should be able to apply vacuum directly to the valve itself and see it pull against the spring - just not sure if that would then CLOSE or OPEN the valve. I have a feeling that the heater core is continually full of hot coolant and that's why the A/C just isn't cooling like it should.

Tom M'Guinn

If the heater valve is stuck open you'd probably feel heat when the A/C is off. As for the control valve operation, a video's worth a thousand word....

User 52121

Thanks Tom, appreciate it. Will watch that vid when I get back home tomorrow. Won't play on my iPhone. Says its unavailable

User 52121

Got the vid to load with some creative editing. Perfect, exactly what I was looking for.

When AC is on, temp set to cold, I should expect full vacuum to that valve?

Tom M'Guinn

Just checked and, yes, with the AC on full blast and the temp set to full cold, the heater valve is pulled fully closed (i.e., the plunger is pulled all the way in). That said, on a hunch, I also pulled the vacuum hose off the valve so it opened, and have to say I didn't notice any difference in the A/C temp -- still seemed plenty cold (and it's almost 90 here today). I guess the flaps block it even though hot coolant is getting to the core. At any rate, I'd focus on the a/c -- you can get a set of gauges for like $50 at harbor freight and youtube is full of videos on how to diagnose a/c systems -- or the climate control box... (Of course, if the heater valve is staying open I suppose you'll want to fix that too....)

User 52121

First off - thanks a bunch for taking a look on your car. Appreciate it man!!!

I have A/C gauges, it's fully charged. (Dad is a former mechanic, I have access to all his tools - which is 2 giant Snap-On boxes full... lucky me!)

I found the issue with the HCV - the vac line that ran to it was split (one of two original hard plastic vacuum lines left in the car). My hands are too big to reach the nipple on the firewall with the motor in the way to fully replace the whole line so I went ahead and just pulled the heater box out of the vacuum loop completely. So now I have a vac line that runs from the check valve, to a T, with one end going to the reservoir tank and the other running to the HCV. So for sure that valve is closed full-time. (By the time it gets cold enough to need heat around here the car is parked for the season, and worst case, I can just re-do the lines to open the valve at a later date should I need heat before the motor comes out again).

2 hour trip into work today, warm out (~80) but rainy and humid. A/C on (recirc off) 45 degrees coming out of the vents the whole way in.

Tom M'Guinn

Great, glad it worked out. I was able to get at those ports from below the car, but they are a pain from any direction!