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Topic: Dash removal for heat exchanger access? (Read 1628 times) previous topic - next topic

Dash removal for heat exchanger access?

Good evening.
I have had my coach parked for a few months with furnace thermostat (zones 1 & 2 )set at 49F. Aquahot  set to use 110v.  I checked antifreeze in Aquahot about a month ago and expansion reservoir was empty. It was serviced about 2 months ago and filled to within hot/cold levels.  I filled it to proper level and ran the diesel burner for about an hour to exercise it. Checked reservoir today and it was once again dry.  I investigated all heat exchangers  but the dash for leaks and all were dry. I checked under the coach in the dash area and the ground below and behind front step was wet.  Also wet behind the step cover. So I am looking to remove the front center and passenger side dash to get access to the heat exchanger. I found the excellent pictures that Rich B posted about 9 years ago. My question:  Is the 99 U320 dash removed similarly as the 2002. 
Thanks
Daniel

Re: Dash removal for heat exchanger access?

Reply #1 –
Daniel,

There is a better example of your style dash removal somewhere. I will snoop around and see if I can find it and post a link to it. Seems like they were working on the expansion valve and had the dash apart.  I have had several apart and the hardest thing is finding all the screws that are hidden. The kick panel in front of the passengers seat just pops off after you remove the switches. Your center section will pull up and then you can see screws to remove it. Just follow the screw trail till you get to the A/C-heater box.

Mike

Re: Dash removal for heat exchanger access?

Reply #3 –
Chuck,

You got to it before me.

@ Daniel,
Here is where Dave had his apart. Heater core replacement

Mike

Re: Dash removal for heat exchanger access?

Reply #4 –
You guys are awesome. 
Many Thanks

Re: Dash removal for heat exchanger access?

Reply #5 –
Good luck in your job and post pictures and results when you're finished please so others can learn.
 I had pulled most of my dash apart to recover it it didn't go all the way down into the nitty gritty of the heater core in the dash but I did not find getting in there hard. I installed some speakers I replaced some other things that I can't even remember what it was now and had the dash completely apart for about a week. Had to recover everything because the previous owner had cats and they had left holes in all the vinyl throughout the coach. One thing I do have a problem with now though it is my temperature control for the dash AC and heat. On my coach with the aqua hot there are seven or eight wires attached to it. Foretravel does not have a part for it or at least they didn't the last time I was there. I've tried online vendors that deal with RVs and was told that there should only be three wires coming out of it. But of course that is with the normal furnace maybe not aqua hot. Would like to get that replaced and I think I'm going to have to find the part number on the evaporator to try to figure that one out.
Anybody know why there's so many wires coming off the temperature control on the dash? Inquiring minds want to know.

Re: Dash removal for heat exchanger access?

Reply #6 –
Bob they all go to the heater control valve up above the headlights on the passengers side
of the coach. When mine quit working it was the motor on the control valve. I didn't know
how to get at the valve so I cut a hole in the front of my coach and then installed semi truck
headlights. Now I have way better headlights and access to the valve. I know all the parts are
available and I will see if I still have the part numbers. 

Re: Dash removal for heat exchanger access?

Reply #7 –
The part number on the motor assembly and I'm sure I threw it away. I got the valve assembly
from Fortravel. I just used the motor assembly and still have the new valve as it was way easier
to just changed the motor assembly. I know the switch is available as when I had the part
number it showed up.

Re: Dash removal for heat exchanger access?

Reply #8 –
Cold front moving thru yesterday 18F outside so I did not get anything done other than lift the top of console.  It looks very crowded and intimidating to remove the heat exchanger/core.  I did not see any visible signs of leaks.  When it warms up I will take another look.    Thanks for all the pictures and detailed instructions. 
Dan

Re: Dash removal for heat exchanger access?

Reply #9 –
I was able to start dash/ console  removal to search for the antifreeze leak. I took top part of console off by the hinges. I remove the four screw on bottom of console where they attach to the floor and the 1 on the driver dash side and the passenger side at the top. Console is still solidly attached and I am not able to see where  or what is holding it. However may not have to go any further.  after removing the duck hoses I was able to view the heat exchanger and search for possible leaks. The floor was dry and no visible  evidence any where from around the heat exchanger or where the hoses pass through the floor. The pass through hole is located behind the electrical bus panel on the passenger side.  Below the deck or looking up from  behind the passenger side headlights there are a bundle of hoses and electrical cables tied together. There is antifreeze leaking down inside the wire loom carrying 2 red electrical cables. I was not able to slide under the coach further to see where they pass through the floor from the underside. I am guessing  the leak is under side of floor close to the pass through hole in the floor.  Since the aqua hot is loosing antifreeze I suspect it is where the pex joins the bundle of hoses and cables just below the hole in the floor.  I do not know how to post pics from my phone yet so will post them when I learn how. My question is this:  Is the pex from the Aquahot all one piece going to the console heat exchanger or is there a joint where it comes through the floor?  More to come.

Re: Dash removal for heat exchanger access?

Reply #10 –
I discovered the hard way on my coach that there are many places throughout the bus that the Aquahot coolant lines switch back and forth between pex and 5/8 heater hose.  It seems that the factory's method of making this connection was to slide several inches of the pex into the heater hose since the o.d. of the pex is about the same as the i.d. of the heater hose and secure this with a spring type hose clamp.  One very cold morning I turned on the Aquahot so I could do some work inside the coach and before I could figure out what was happening about 5 gallons of antifreeze was flooding the living room and running down the entry steps.  I discovered the separated connection at the heat exchanger under the living room cabinet.  I decided to put this connection back together using a 5/8 barb fitting and a 1/2 pex fitting threaded together.  Then I realized that there are at least a dozen other places with this same potential problem.  It has caused me a few sleepless nights as one of those coming apart undetected would empty the Aquahot boiler in just a few minutes.  It is an easy and cheap fix however compared to a failed heat exchanger.  Good luck.

Re: Dash removal for heat exchanger access?

Reply #11 –
Thanks for the reply and great photos.  Helps to know what to expect. It looks like after Christmas be for I can get back to the project. High for tomorrow is -1 in Colorado Springs.
Merry Christmas to all!

Re: Dash removal for heat exchanger access?

Reply #12 –
After many days of cold weather and holidays I did get to the heat exchanger removal. The leak was a 10"  section of heater hose located at the support bracket  supporting hoses and wiring harness behind the front steps. I figured since it was close to the heat exchanger unit I might just replace that 6' section. That was a big mistake. In the process trying to break the hose loose from the heat coil I egg shaped the copper nipple. After replacing the 6' section tightening the clamp to check for leaks it appeared to be leaking from the inside. I ended up removing the whole exchanger unit  to find only  the egg shaped nipples were the only leaks where the hose to heat coil did not seal.  I reshaped them to be round and put it all back together using worm clamps at all hose to nipple  connections. Now it appears to be tight with no leaks.  Next step is to install all the air duct hoses. I do not have a photo of where they go from the manifold. Does anyone have a schematic , diagram or photo of the manifold air duct to vent installation?




Re: Dash removal for heat exchanger access?

Reply #13 –
See if your hoses have "memory" to them . After 20 years they should retain their shape and would probably retain whatever configuration they were in,

Re: Dash removal for heat exchanger access?

Reply #14 –
Yes, they have a better memory than I do!  That was my last resort. 
Thank you

Re: Dash removal for heat exchanger access?

Reply #15 –
I have this....

Re: Dash removal for heat exchanger access?

Reply #16 –
Thank you that will help a lot.  Know the position how they come off the manifold is monumental.