Hi everyone,

I finally got some time to work on Tonka this weekend and we are on a roll trying to figure what's working, what's not, what I might be able to fix and where the line is for me to seek professional help (my wife has a pretty clear opinion on this one).

Bringing Tonka home from Kentucky last fall, the AC compressor locked up and spit a belt. As cold as it was, we weren't trying to run the AC but were fumbling with the controls in the dark and rain to help the overhead fans defrost the windshield.

While we were fumbling the control lever stuck in the far right warm position. As I peck at my "honey-do' list I finally got around to checking it. The cable is bent at the dash control and needs to be replaced. I should be able to handle the cable replacement. More significantly the valve arm it moves acts like it is locked up tight as a drum.

What is this valve? Is this likely a mechanical or pressure induced lockup? Is this repairable by someone with a high level of care and good intentions but with limited mechanical knowledge and skills or does this need an AC/HVAC pro?

Photo of valve.



I think there is a second part to this issue. This spring we noticed a regularly spaced but intermittent buzz in the dash and traced it to a valve that I think is part of HVAC vacuum system. At about 5 minute intervals it buzzes and purges air/vacuum.

Any information, direction, thoughts or advice is appreciated. I'm hoping this is all fixable from the front access bay or under the dash and that the dash doesn't need to be taken apart to get at an air box vent door or something.





Thanks,
Wally

That valve looks like the coolant bypass that would send hot coolant through the heat exchanger or not.

Interesting that the compressor froze up since Days RV was supposed to have put a new one on. Did you call and ask if it is under warranty?

It won't matter much anyway, that dash AC is the worst I ever dealt with. It works when outside is under 75. I suppose it helps the defrost a little, but that's it. I got very used to running the generator with the roof airs to cool the old girl down.

Just when I was waxing nostalgic about my time with your Barth, you brought me back to the things I did learn to despise

The valve in the top photo controls the supply from the engine (heat) to the heater core. You can remove the cable and work it by hand.

The detachment of the cable at the dash control lever is common,and a replacement is sometimes warranted. However, this detachment is caused by moving the lever to the "Heat Off" (pushing on the cable, which detaches it from the bracket).

It may not be necessary to replace the cable. I had a similiar issue, and coated the external wires with J-B Weld and reinserted that end into the socket. I then added more J-B weld to the exterior, wrapping it while wet with fine wire.

I should have mentioned the valve can usually be exercised and freed up. It's simple to replace, if necessary.

Thanks Corey and Rusty,

I talked/emailed Day's right after we got back last fall but didn't aks about any warranty. I've got so much time lag actually getting to anything that I doubt there would be much chance of any warranty satisfaction this late in the game.

In our climate the dash AC in most cases isn't a priority except occasionally to help defog the windshield. I just don't know/understand the functions of all the components in the dash. I like to try to understand what's what to determine if I want to take a crack at trying to fix something or cut to the chase and take it to a shop.

The planet will like me better if I leave any AC work to the pros with the knowledge, experience and tools.

I know I can repair or replace the HVAC control cable if I can find the right one and now that I understand that I'm dealing with a heater core water line I'll see if I can free it up.

Do you know what the vacuum valve is and what it is trying to do and if the intermittent purging is just a normal operation or something that needs to be looked into?

Thanks, really appreciate the info and advice,
Wally

If you do need to replace that heater bypass valve, I'd like to know a source. I will need one soon when I get to finishing the work on my heating/cooling vent controls.

http://www.midwest-autoparts.c...R%20SEASONS&weight=1

This is the replacement that worked best on a straight hose.

http://www.airproair.com/pdf/i...TER%20VALVES-new.pdf

Look at 45-4007 for the bypass type (like your picture)

BTW, the last pix is the vacuum pump.

Thanks Tom for the parts source.

Looks like the OEM Part No Kysor 173090, Airpro Item Part No 45-4007 "H" Type Bypass will be the one I need if I can't free it up.

Thanks Rusty for ID'ing the vacuum pump. Is it supposed to purge intermittently or is that likely part of a leak or different issue?

Wally

It'll run occasionally, but it's not capable of a 100% duty cycle. Ed (MWrench) found it wasn't robust enough, and replaced his. On mine, the original vacuum pump ran continuously (as it was designed to do) and died.

This one has a vacuum switch and cycles a few seconds every few minutes. My system is free of leaks, so I suspect the pump leaks a little.

Thanks Rusty,
Wally