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760 84 760 acc?

Dirty Rick

Dirty Rick

Active member
Joined
Apr 10, 2013
Location
Cornholio, OR
Got the heater core and blower motor in, recharged the AC and that is happy now.

But I have a question I haven't found an answer to yet.

This is ACC not ECC

Can you force it to Max AC I don't see how.

I am not seeing the hot water valve close, it defaults open right?
 
https://www.volvoclub.org.uk/faq/HeatingAirConditioning.html

I don't know your setup, but if using a vacuum controlled water valve like this, then its controlled via rotary switch inside vehicle. With engine off, one could pull its vacuum line off and observe it...or drive around town with rotary switch in cold position, and blower fan set to high...any heat coming out ducts means this water valve is not working, or vacuum is not being applied to water valve, if it works this way...maybe reverse.

Or just pull its vacuum line, have someone start engine, and turn rotary switch in both directions while someone feels for vacuum at pulled vacuum-line hose from water valve.
 
This is an Automatic Climate Control system not a Manual or an Electronic Climate Control.
It is a stump stupid electro-mechanical pinball machine equivalent control system

You can disable the AC but I don't see a way to force Max AC or test the water control valve operation.

I purchased the green book Section 8 (87) that covers Climate control to work on this.
But it does not give any theory of operation, or even operating instructions.
It has a vacuum matrix chart, but no explanation or testing procedure for the "programmer".
 
Dirty Rick said:
test the water control valve operation...
Click to expand...

Either it is mechanically controlled, or via vacuum...I explained how to test vacuum at water control valve.

"HVAC" systems can be manually rigged....ducts will flow air as you determine, AC switch to engage compressor using OEM pressure-switch safeties, fan switch to control fan, and manual water turn off/on valve.

Semi-trucks have used manually controlled water turn off valves for years, when AC is used.
 
If I disconnect the vacuum line to the programmer diaphragm it will go to max AC.

Do I have to heat the interior temp sensor with a hair dryer to trick the control system?

Turning the temp knob to less than 65 does not create enough change in the programmer position to cause it to go to max AC.
 
I tested all the sensors before installing the system.
All measured in spec.

All indications at this point it appears the Programmer vacuum regulator is not happy. since everything around it appears good.
I hate to shotgun it without proving what is wrong

84 760 or equivalent 90- 740 up thru 87 760 & 780

The black plastic programmer mounts behind the left side of the glove box with 3 screws and one linkage to the blend door.
The vacuum harness connects to it as well as blower speed control and the temp control loop.
The system can be quickly identified by the simple control panel, a mode slider and a temp thumb wheel are the only controls.

Anyone parting out? Hoarding spares? How many rolls of TP is this going to cost me?
 
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