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Dash AC question

My dash AC is pulled apart now to get the condenser fixed.  I don't know a lot about dash air except that I had a lot of trouble with it last year (cracked fitting at condenser, bad low pressure switch, air only coming out of the defrost vents, to name a few).  But today I finally figured out that there is something called a receiver/drier in the line with a desiccant cartridge to remove water.  I looked around and found this, which looks a lot like the image posted by Robert (rsihnhold) in a previous thread.  So I think that's it and it looks like it is probably original.  One of the documents on Barry's site says that it should be replace like once a year or so.  So the question is, should I try to get it replaced at this time while the system is empty anyway.  What would the part number be that I'm looking for and can I get it through local auto parts.  And how difficult is it to replace it? The connections look pretty crusty.  I do not have it at an air conditioning shop, just a local garage that does a lot of my routine maintenance.  They have not seen one of these before and I don't want to cause more problems.

Thanks
BJ

BTW, finally figured out that the problem up front in the doghouse was a bad relay on the circuit board that runs the little electric motors that move the doors, and that's why all the air was always going out the defroster.  I ordered up a bunch of the relays and replaced the bad one and now that part works again so I have more relays if anybody needs them.

/Users/bj/Documents/BJ/E3/Documentaion/E3rcvrdrier.jpg
BJ Holden
'98 U320 36'
Motorcade #16754

Re: Dash AC question

Reply #1 –
Looks like my drag and drop to insert the picture didn't work.  Guess I don't understand how to do that.
BJ Holden
'98 U320 36'
Motorcade #16754

Re: Dash AC question

Reply #2 –
Quote from: corndog254 –
My dash AC is pulled apart now to get the condenser fixed.  I don't know a lot about dash air except that I had a lot of trouble with it last year (cracked fitting at condenser, bad low pressure switch, air only coming out of the defrost vents, to name a few).  But today I finally figured out that there is something called a receiver/drier in the line with a desiccant cartridge to remove water.  I looked around and found this, which looks a lot like the image posted by Robert (rsihnhold) in a previous thread.  So I think that's it and it looks like it is probably original.  One of the documents on Barry's site says that it should be replace like once a year or so.  So the question is, should I try to get it replaced at this time while the system is empty anyway.  What would the part number be that I'm looking for and can I get it through local auto parts.  And how difficult is it to replace it? The connections look pretty crusty.  I do not have it at an air conditioning shop, just a local garage that does a lot of my routine maintenance.  They have not seen one of these before and I don't want to cause more problems.
Thanks
BJ
The drier is inexpensive and I would definitely change it now since you have it apart. Your mechanic should be able to cross reference it to locate one.
The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"

Re: Dash AC question

Reply #3 –
Hi BJ,  Your drag n drop just put the link to a file on your computer, not the file itself.  As an alternative you can click on the words "selecting them" and you will get a chance to select a JPG file on your computer to upload.
Filter dryers should be periodically replaced, but anytime they are replaced the system must be evacuated and recharged, so the time is when the refrigerant is out.  Probably not a good idea to empty a working system just to change filter dryer.  I think most filter dryers are about the same, just different sizes and connections.  Not sure the part number, but removing yours, taping up lines to keep dirt out and taking it to an auto parts store so it can be matched up should work for you.
Use lots of nut buster because a very rusted connection may twist tubing.

Re: Dash AC question

Reply #4 –
Filter/driers only need to be replaced when the system is opened up.
1998 U270 34'

Re: Dash AC question

Reply #5 –
If you can find one of those gear motors that would be a good spare to have.
They may be getting hard to find.
I had one go bad in my '95 and got one from FT.
That was about 7 or 8 years ago. Wonder if they are still available?
JD
John Duld
1995 U320C SE 40'

Re: Dash AC question

Reply #6 –
Would it be possible to send pictures of those little 12v motors and also the relays.
1995 U320 40', 2013 chevy sonic toad, my real love are corvettes have owned 30

Re: Dash AC question

Reply #7 –
Is the filter dryer located behind the dog house? Any one have a picture of it. John
John
1998 U270 34'

Re: Dash AC question

Reply #8 –
Our filter dryer is located above and forward of the isolator panel, which is mounted above our large air dryer in the small "compartment" door behind the rear street-side tires.  Filter dryer is attached to the frame.  The dryer is not far from the condenser mounted  inside the rear street-side fender.

Re: Dash AC question

Reply #9 –
I will send out pictures and info about the dash ac work I got done last sept in Nac.  But got to run now, I'll send it out tonight when I get home.
BJ Holden
'98 U320 36'
Motorcade #16754

Re: Dash AC question

Reply #10 –
First, thanks to the folks who rapidly replied to my questions about the receiver/drier.  I ran back down to the garage and they got the NAPA guy over to look at it and it turns out they had a replacement so I was able to get that done while the system was still apart.  Seemed to be cooling good on the way home.  Only time will tell if I have any leaks.
OK, this is more than the requested pics of the parts but the information might be useful to some folks, including the one who sent me a personal message.  As always with this stuff, I learned a lot more than I ever wanted to know.
Basic problem was that all the air blew out the defroster vents.  I found out that for several, including 1998, my year, they used electric motors instead of vacuum.  I took it into FT last Sept.

 Instead of rewriting it I'm just inserting a copy of my notes ....
Took doghouse apart.  Alton figured out that relay was not working.  There is a small printed circuit board with 3 dpdt relays that control doors.  12v control lines from dash switches energize coils on dpdt relays.  When switched the relays reverse the polarity across the dc motors that drive the doors to open and close them.  The relay that controls the big damper door that switches airflow between dash and defrost was not working.  FT cannot get the control board anymore.  I found the relay on the internet and got it delivered.  Took it to Nacogdoches Computer to replace and they could not melt the solder.  Never heard of that but there is solder out there that does not have lead and has higher melting point.  He burned the board trying, and said that he would destroy the board before the solder would melt.  Gave board to Bernd and he did a perfect replacement job.
Back into FT to put doghouse back together.  Worked with Rickey.  Bernd brought over repaired board.  Plugged it in and tested it.  Relay was working ok and reversed voltage but motor would not turn.  Replaced motor and it worked good.  Did voltage measurements.  In quiescent state there is about 6.5 volts across motor, rest is dropped across resistor that is in series with it.  When control line is switched voltage across motor jumps up to about 11v until motor finishes turning, then drops back to 6.5 v.  Motor turns very slowly with gearing, and only about ΒΌ turn.  That one drives two doors, one below and big one above.  Still not getting much air out of system.  Patched some holes in tar paper? sealing stuff.  Also shut off two vents going to passenger side to get more out of driver side (I can do that because there is only one of me).  Better, just not ever going to be good.  Too much turbulent flow in the system and a weak blower.  Took out plug on top of plenum to see what was in there.  Can see the big door opening and closing.
Then, while I was taking voltage measurements,  I managed to get the board too close to the sheet metal plenum and got a big flash.  Shorted a 12v line to ground and a short piece of trace on the board vaporized.  Bernd fixed it again.  Going to leave board laying in bottom of doghouse where I can reach it from the top, instead of remounting it where it was.  Wrapped it up in cardboard and blue tape to protect it.

So that's what happened then.  Here are some pictures. They show the linkage between motor and door, the motor as mounted,  closeup views of the motor, circuit board and relay for parts ID, and the last one shows the board where I chose to leave it. I wrapped it up so it wouldn't short onto the sheet metal and it fits snugly there.  I can get at it from the top if I ever need to change out another relay.  Normally the board would be mounted up in the opening above it, behind the sheet metal. 



BJ Holden
'98 U320 36'
Motorcade #16754

Re: Dash AC question

Reply #11 –
Earlier coaches used cables. Consider switching. other options - see the innovators in this business:
Classic Auto Air - Air Conditioning & Heating for 70's & Older Cars & Trucks.
Custom Aftermarket A/C Systems & Replacement Parts for Hot Rod, Classic, &...
Custom Aftermarket A/C Systems & Pro Touring A/C Parts: Hot Rod...
Vintage Air - Inventors of Performance Air Conditioning - www.vintageair.com

A couple of these are in Texas.
The selected media item is not currently available. Dave Head & Megan Westbrook
Titusville, FL - The Great Outdoors
'98 270 buying this month
Toad is a 2018 F150 XLT

Re: Dash AC question

Reply #12 –
" Instead of rewriting it I'm just inserting a copy of my notes ..."
EXCELLENT post, BJ.  Thank you for going to the trouble of sharing the details.
Mogan David
1999 U295 36'