AC/Heater Blender Door

[Tajefe Couple]

Any advice on if my below problem is blend door related. Help appreciated.

My Ac seems to get warm whenever it feels the need while driving. All temps except IAT almost always have the same readings when it happens. The consistent is IAT is always in the 110-120 range when the AC starts getting warm. Always happens when driving but not always when IAT goes up and never change the AC settings. Can shut the car off for a few minutes and back to cold air, or just be driving with no setting changes and again back to cold air.

Expansion valve maybe? Going to buddys this weekend and put a pro set of gauges on it instead of my cheap set and try to troubleshoot from there.

[uvraise]

I still didn't want the heat to creep, so I installed 2 valves.

Originally Posted by CamaroFred

Back in the 1970's - '80's, before A/C was standard equipment, vehicles with A/C had a vacuum controlled valve in the heater core feed line. The colder the dial was set, the more closed it was.
Our work trucks didn't have air and the flow-through ventilation pumped heat all the time.
I would go to the hardware store and buy a water shut-off, two hose adapters, and two worm clamps and put it in the feed line.
Some heat is still transferred, but not nearly as much as when the coolant circulates.
Here, in the upper midwest, it was as easy as close the valve in the spring, open it in the fall.

Now, for some reason unknown to the sane people in the world, they have done away with that vacuum shut off.

One valve is all you need. Any kind for fluids works, even the cheapest ones.
Don't buy one for natural gas, those use grease as a seal and hot coolant will flush that out.

[uvraise]

Well, my suspicions were correct. I closed off both the supply and return lines to the heater core with valves. It worked like a charm! I'm now getting 46 degree air from the vents as opposed to the 80 I was getting. The temp here is now 91 degrees out, so looking at the chart I found online, the temp from the vents is a little better than average. In the fall, I'll just open the valves.

[Tajefe Couple]

Originally Posted by uvraise

Well, my suspicions were correct. I closed off both the supply and return lines to the heater core with valves. It worked like a charm! I'm now getting 46 degree air from the vents as opposed to the 80 I was getting. The temp here is now 91 degrees out, so looking at the chart I found online, the temp from the vents is a little better than average. In the fall, I'll just open the valves.

Would you mind sharing what valves you picked up and where you got them?

[PowertoLove]

The sad part of all this is replacing the blend door doesn't fix it. It will just break again. The actuator needs to have a mechanical stop so when the electronics fail the actuator doesn't move so far that it breaks the door off.

To repair mine all I did was take a hose clamp wrapped the heater hose with a piece of heater hose. Then put the hose clamp over it and tightened it up until flow through the heater core was reduced. I still get heat if I need it and the AC is ice cold.

[sixty9fordkiller]

Powertolove - I too have read (in this same forum i believe) that some have done the correct repair (windshield and dash out) only for it to fail again. The very reason i decided against it at the last minute. I almost took the car in 2 weeks ago to get that done. Cancelled the appointment the day before.

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[xc_SS/RS]

So stopping the flow of coolant to the heater core is alright by using a valve? Tempted to try this to get even colder ac lol

Edit: I think the valve would go on the return line, correct? This way the core stays full of fluid

[sixty9fordkiller]

For the record.....this is the only mickey mouse ish ive ever done to this car. The fact that i absolutely need to do the heater hose relocation (due to an upcoming upgrade) just made it a no brainer. I am definitely gonna do a writeup on this shenanigan. Its the least i could do while saving myself atleast $1700

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[sixty9fordkiller]

Originally Posted by xc_SS/RS

So stopping the flow of coolant to the heater core is alright by using a valve? Tempted to try this to get even colder ac lol

Edit: I think the valve would go on the return line, correct? This way the core stays full of fluid

there needs to be coolant flowing through both waterpump heater hose tubes or else the car will not like it

will need (2) shutoff valves and and "H" pipe as a bypass/bridge

[xc_SS/RS]

Originally Posted by sixty9fordkiller

there needs to be coolant flowing through both waterpump heater hose tubes or else the car will not like it

will need (2) shutoff valves and and "H" pipe as a bypass/bridge

Why not grab one of the vacuum diverter valves and hook up a C3 Corvette headlight switch to the vacuum line? This way you have the switch in your car and heat/AC when you want it

I will be grabbing one of these:
https://www.amazon.com/ACDelco-15-55...C2QPCKGFSZFF5S

And I've got the C3 headlight switch from my NPP install that's now useless since I keep the system open all the time lol now I'll have a use for it again

This I think will let some coolant flow to the core to keep the fluid fresh

[PepeLePew]

Originally Posted by sixty9fordkiller

there needs to be coolant flowing through both waterpump heater hose tubes or else the car will not like it

will need (2) shutoff valves and and "H" pipe as a bypass/bridge

Very nice diagram! Thanks for sharing

[sixty9fordkiller]

keep in mind, 5/8 hose is TO HEATER. 3/4 hose is TO WATER PUMP

[sixty9fordkiller]

Originally Posted by xc_SS/RS

Why not grab one of the vacuum diverter valves and hook up a C3 Corvette headlight switch to the vacuum line? This way you have the switch in your car and heat/AC when you want it

I will be grabbing one of these:
https://www.amazon.com/ACDelco-15-55...C2QPCKGFSZFF5S

And I've got the C3 headlight switch from my NPP install that's now useless since I keep the system open all the time lol now I'll have a use for it again

This I think will let some coolant flow to the core to keep the fluid fresh

I used that before in my 69 camaro (thats where my screename comes from btw ) and they are prone to failure. With these flow valves, im planning on opening them once a week and letting coolant circulate. I know where you're coming from. I dont like the idea of coolant just sitting in there and not circulating

[sixty9fordkiller]

get a brass one if you do go that route, xc_SS/RS. My experience is that the plastic ones get brittle and crack over time.