Saturday, March 02, 2024

A Bypass to Re-establish Vacuum Functionality

 For quite a while now, there'd been something preventing the flow of Air Conditioning through the dashboard vents.  AC would only flow from the defrost vents at the base of the windshield!

We put up with it since things were eventually cool enough during driving periods but now that warmer weather is on the way, it was time to figure it out.

I'd replaced the blower motor some time ago, no joy.  Then it occurred to me that it might be an actuator problem instead.  The VRRV, uses vacuum to turn on actuators which pull spring-loaded levers that open/close appropriate vent doors to provide functions such as AC air, defrost, floor air and vent as required.  (see video for actuators)

I found the below YouTube video which enabled me to fix the issue (I should have begun the troubleshooting here).  I bypassed the vacuum canister and now I have working AC vents and the other functions work as well.  More testing to follow since I only tested with the engine idling but I have high hopes.

In a conversation with RichardM, he confirmed bypassing the vacuum canister should be OK, its function is to maintain vacuum pressure levels when the engine is under heavy loads.  Time will tell with the VRRV.

The vacuum hose I needed was 5/32" ID (Inner Diameter).  I got six feet of it at the Pecos, TX AutoZone store today (I guessed at the diameter, should have actually taken the connector fitting on the VRRV with me but forgot). Cost $12.

I tested before threading the bypass hose and it worked!  Eureka.  I then ran the hose as described in the video.  Then I used a suitably trimmed drywall screw plastic anchor to join up the tube that used to connect to the vacuum canister and the bypass hose:

In the above pic, the hose on the left is the bypass hose with the drywall anchor.  The right hose I pulled off the vacuum canister (luckily, nothing had to be removed to get it to come loose!).  The object at the end of the hose is a check valve to prevent vacuum from back feeding I think.

Of course, given my meager skills with tools and troubleshooting, this took all morning and part of the afternoon as well since I tried several things to get to the current condition.  I also used the CR-V to drive the 25 miles or so to Pecos, TX where the Autozone was located.

Now I only have to return the vacuum pump I thought was correct for the VRRV (it wasn't) via Amazon.

Though a bit windy at times, the sun's warmth led to temperatures in the low 80s for this area.  Nice.


RichardM said...

Nice repair! Macgyver would be proud…

redlegsrides said...

Thanks, McGyver would have done it in ten minutes!

CCjon said...

Now I know who to call the next time my sidecar rig acts up. Good fix!

redlegsrides said...

Thanks, CCjon, I got lucky in finding the right YouTube video and of course they ever helpful RichardM!