Heater control valve not connected (4 Viewers)

[tasmaniandevil]

Hello,

Need help again.

The AC of my 97 LC stopped working, all warm air. Low pressure side is 20pis, high pressure side is 100 with 650 idle rpm. Put 4/5 can in, now I got 60 on low pressure side and 120 on high pressure side with 650 idle rpm. 40psi low pressure side and 150psi high pressure side with 1500 rpm. Temperature is 75-80F. Too high ?

The dash temperature didn't change at all.

People say the heater control valve cause problem sometimes. Mine seems not connected but the hot cold slide works ok, hot air came out instantly once moved over. The swing arm of the heater control moves accordingly.

What should I do next?

Thank you

 

[Fj80oregon]

the heater control valve has no control! Yes you need to hook up the valve correctly, you just need a couple hoses and clamps to achieve this. looks like someone bypassed the rear heater but did not know what they were doing. Search rear heater bypass and hook it up the correct way and you should be back up and running with cold air. Right now your heater core is getting hot coolant flowing through it and no matter how cold the AC is it can’t cool 185 degrees to 50.

 

[baldilocks]

You might consider replacing the hot water control valve. It looks old.

 

[Kernal]

@tasmaniandevil : Can you show us the other heater hose plumbing on the firewall, ie: middle and right taken from above and/or from the right looking at the firewall.

 

[tasmaniandevil]

the heater control valve has no control! Yes you need to hook up the valve correctly, you just need a couple hoses and clamps to achieve this. looks like someone bypassed the rear heater but did not know what they were doing. Search rear heater bypass and hook it up the correct way and you should be back up and running with cold air. Right now your heater core is getting hot coolant flowing through it and no matter how cold the AC is it can’t cool 185 degrees to 50.

I will do that. Thanks a lot. BTW, will it have impact on the ac manifold gauge? Right now I am high on the lower pressure side and low of the high pressure that.

 

[tasmaniandevil]

You might consider replacing the hot water control valve. It looks old.

Good point. Thank you

 

[tasmaniandevil]

@tasmaniandevil : Can you show us the other heater hose plumbing on the firewall, ie: middle and right taken from above and/or from the right looking at the firewall.

Thanks

 

[ZackR]

Not the photos I was expecting to see based on the title of the post!

I concur with @Fj80oregon 's post above. Order new valve and put it back together correctly before messing with the AC any further.

 

[Kernal]

OK, so the rear heater circuit was disconnected and left in place, the T pipe removed on the right, and front heater hoses rerouted directly to the front/main heater core pipes on the firewall. So as already mentioned above, your front/main heater will get hot coolant all the time no matter where the heat selector lever is positioned.

By the looks of the bracket for the rear heater pipes and other brackets in the photo (rusty) the rear heater pipes could have been rusted through and leaking, so the PO bypassed them in his own way. Where did the vehicle spend most of it's life?

@tasmaniandevil : If you haven't looked yet, get under the vehicle, look up, right side above the Catalytic convertors if your model has them (under the front right foot well and front right seat) and take some photos of the rear heater pipes, they are mostly hidden by heat shields but you can see some sections of those pipes.

 

[LongDuck]

Post #2 seems to nail it; the PO bypassed the heater control valve, and in doing so you now have hot engine coolant running through the heater core ALL the time, which the A/C can't overcome. If you need to bypass the rear heater because it's leaking, here's the correct way;

On one of my other cars, the A/C is so anemic that I bypassed the heater core so there's zero hot coolant going to it to maximize efficiency. In the Sonoran Desert every little bit helps,

 

[cartercd]

Once you get your plumbing sorted, see this post to set up the adjustment cable on the heater control valve Adjusting water valve to maximize A/C performance - https://forum.ih8mud.com/threads/adjusting-water-valve-to-maximize-a-c-performance.173731/