So I have been (and the mechanic) trying to trace down a strange issue. When my truck is under load. The heater defaults to front vent. (driving around town is mostly fine.) So when cleaning out my floor I looked up and notice a 2 hard vacuum lines by the driver side floor cent. I was wondering if they are broken? Tried to test with the truck started and I think i got vacuum in certain heater selections. It was hard to tell. So I placed a piece of hose and put the two Together. See if that helps. Can you tell me if that normal or not?

Thanks,

Josh

 

I've never heard of the hard vacuum lines under the dash going bad. Were they still connected to one of the actuators?

The more likely problem is that you have a leak in the engine compartment vacuum lines. These are known to rot. I have a link to my vacuum line replacement thread in my signature below.

 

For the last year I owned it. Me and the mechanic had replaced all the lines under the hood. When I first got the truck. I had to replace a section asap because it wouldn't even go into defrost. Also I keep getting a check engine light on 2nd air intake system. You can hear the pump kick on an see a sensor. I believe it also needed a vacuum line. But I had those replaced to get the 4 wheel drive working. So me and the mechanic is still thinking a leak some place under engine load. As for the lines. No I cannot. They just head up in that direction. I have not taken the dash plate off since I was just cleaning today. But sound like somebody did something at one time. So when I get around to adding my back up cam. I'll try to look and see what places they go. It reminds me of the hard vac lines that goes through the firewall. But the heater controls work. TTFN, Josh

 

Usually with a loss of vacuum during a load situation the vacuum line is off the vacuum res. ball or the ball it's self is bad. May not hurt to take a second look .....

 

I know the ball is connected. I tried to bypass the ball. But I'm thinking how would I test the ball. I don't have a vacuum tester.

thanks,

Josh

 

You might be able to borrow a vacuum tool from a local parts store. But in a pinch, take the end of the hose coming from the vacuum reservoir and suck on it with your mouth and then plug the end with your tongue. It should hold vacuum for at the bare minimum of several ten's of seconds. If it doesn't, it is bad and needs to be replaced.

BTW, I know this might not be the most sanitary! LOL