Slide problems

Topic: Slide problems (Read 183 times) previous topic - next topic

Slide problems

April 07, 2021, 10:39:16 pm

My coach is in my shop with the slides out.   I couldn’t get either one to go back in.   My 12V compressor will only build about 50 pounds and runs all time. (The previous owner put a gauge on line 75.)   There is a ball valve on line 76 (Schematic B-2254) so I’m not losing air there.   I don’t hear any air escaping in the bay other than when I have the Venturi operating with the slide key on.

I wondered if the “air tank” switch valve is bypassing but I don’t see it on the schematic and I don’t know which line it is on. I figured it was on line 76 going to the wet tank.

I finally got the rear slide in earlier but the front one does nothing.   The light blinks and the seal goes into a vacuum but the light keeps blinking and doesn’t go solid. I can use as paper clip to trick the front vacuum sensor and the light quits blinking and goes solid but the pump still won’t run. The rocker switch must be working because I hear a faint click when I press the retract button.

I’ve tried all the tricks I know to get this slide in but to no avail.

Last year when I was at MOT getting serviced I told them I had intermittent problems with the front slide but all they did was turn up the air pressure switch a little and told me it wasn’t building enough pressure. I continued to have intermittent problems but it would usually work after trying it a couple of times.

The coach is level. I don’t know where to look next.   I haven’t raised the coach and crawled underneath yet. I feel a little like an idiot at this point after so many years with these coaches and being stumped by this.

Re: Slide problems

Reply #1 – April 08, 2021, 07:48:02 am

Air tank switching valve, are you talking about the solenoid that goes to the main air tanks. If so that should be located near the 12v compressor on the tree that all the hoses split off and go to their respective spots. With air pressure on the system go out to the slide seals and see if you hear an air leak there, on my 2003 I’ve had to replace both seals in the last six months due to a pretty good air leak on the seals. If the air leak is bad enough it won’t be able to pressure up and if it won’t be a pressure up the 12v compressor won’t turn off the pressure switch which if it’s like mine is set at about 85 pounds.

Keith

Re: Slide problems

Reply #2 – April 08, 2021, 08:41:10 am

I'm not familiar with how FT evacuates the air from the bladder, is it a venturi vacuum pump?
Anyway, a lot of the Newell guys have added an electric vacuum pump to evacuate the bladder air. If anyone's interested I can dig up that info and post it.

Re: Slide problems

Reply #3 – April 08, 2021, 08:46:49 am

Thanks for the replies.

The slide seals each have a gauge installed and they hold appropriate pressure for weeks with the compressor turned off.

Foliver, you are correct that it is a Venturi vacuum pump and it is working correctly. The seals go into a retracted state just as they should.

I have found the HWH manual that includes the wiring diagrams and will see what I can find there.

Re: Slide problems

Reply #4 – April 08, 2021, 09:20:35 am

Quote from: Johnstons - April 07, 2021, 10:39:16 pm

My coach is in my shop with the slides out. I couldn’t get either one to go back in. My 12V compressor will only build about 50 pounds and runs all time. (The previous owner put a gauge on line 75.) There is a ball valve on line 76 (Schematic B-2254) so I’m not losing air there. I don’t hear any air escaping in the bay other than when I have the Venturi operating with the slide key on.

I wondered if the “air tank” switch valve is bypassing but I don’t see it on the schematic and I don’t know which line it is on. I figured it was on line 76 going to the wet tank.

If there's an issue with the air tank solenoid (which connects the aux compressor to the main tanks), it will likely show up in your Tank A and Tank B pressures increasing with the aux compressor running.

With the switch off (which it should almost always be), turn the ignition to accessory but don't start the coach. All you want is for the display on the Driver Info Center to light up and show you Tank A and B pressures. Watch them when the aux compressor is running. If they go up, the switch or solenoid is allowing leak through.

That said, you mention the aux compressor running all the time. Can you feel or hear air at the bottom of the condensate bowl? That NO solenoid gets debris on the plunger seat and the plastic bowl itself develops heat stress cracks from thermal cycling. The cracking is normally at the fittings at the bottom of the plastic bowl where the solenoid valve screws in. Either of these could cause the aux compressor not to build adequate pressure and cause it to run all the time.

One other member recently had the compressor's head seal fail. Older compressors used a paper gasket. Newer ones use an o-ring/rubber gasket. It's not a common failure, but you can't rule anything out.