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Topic: U225 Dash Heater/AC Fan Quit - SOLVED (Read 821 times) previous topic - next topic

U225 Dash Heater/AC Fan Quit - SOLVED

Well today which coincidentally is the warmest day in a month, the fan on the dash of our '93 U225 GV has stopped completely. The only air through the ducts is from the coach traveling at speed.

I'm pretty sure it was working a couple of weeks ago but it would be intermittent. Now... nada.

I checked all the fuses that seemed appropriate and they're all looking good.

Any hints would be nice.

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: U225 Dash Heater/AC Fan Quit

Reply #1 –
Looks like a vacuum pump behind the grill... it works. When I change the pushbuttons we can hear sounds from inside the unit.

However the two fans on the condenser behind the grill never came on (which I expected to come on).

The 10A fuse at the back of the dashboard labeled "fan" (I think) has 12vdc to it.

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: U225 Dash Heater/AC Fan Quit

Reply #2 –
Craig, On mine there are two relays, one for the Compressor and one for the CONDENSOR fans.  The condenser fan relay on mine is mounted on the fire wall above the vacuum pump.  The compressor relay is mounted with the isolator behind the left rear wheel. Yours may be different.  In addition you know that there is a fan behind the panel on the passenger side.  I found this to be a common chevvy truck blower fan.  Check your wiring diagram to see if you don't have these two relays, them jump them or replace them.
The vacuum pump simply controls the doors in the plenum and the water flow thru the "H" valve.
Good luck
Gary B

Re: U225 Dash Heater/AC Fan Quit

Reply #3 –
The fan runs on 12 volts from the dash contol unit. Low speed would be like 7 volts, the next up speed would be a higher voltage and high speed would be full 12 V. There is only one electrical wire attached to the fan. Check for voltage there. If none, it is the control unit or a wire. If you have voltage, it is the fan.
1994 U280, Build 4490
Deming, NM.

Re: U225 Dash Heater/AC Fan Quit

Reply #4 –
Having just having this problem, to solution was to reconnect a wire to a relay, it is tHE 1/4'' wide push on connector  in the dash. Since mine is the 01 320, I assume it is a different location than mine, but as mentioned, check wiring and voltage, not too bad to solve.
Dave M

Re: U225 Dash Heater/AC Fan Quit

Reply #5 –
Going to have to actually *find* the fan I think.

Gary: I am pretty sure I have both these relays.

Dave M: Finding anything in parts of the dash is .... interesting. A ratsnest of wire bundles. I'll have to look for a loose wire. Or a wire that's become corroded so badly that it fell off its connector. Back at the isolator this would be common... we have found at least 4 of these badly-corroded wires back there that fell apart at the merest touch. Fortunately the fix is to strip the insulation back to good (shiny) wire and reconnect.

Thanks... I will be over to the unit today.

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: U225 Dash Heater/AC Fan Quit

Reply #6 –
Craig, The AC sequence should be.... Turn on to max air, Compressor engages, refrigerant flows thru Expansion valve, temp of refrigerant reaches high point and condenser fans engage, temp lowers, condenser fans cut off, temp goes to freezing at evaporator and compressor cuts off, temp rises at evaporator, compressor engages and so on, its an endless cycle.
Quick checks ( probably not approved by anyone ).  Jump 12 V to compressor, check for cold at entrance to evaporator coil, no cold means refrigerant missing or low. Or you can disconnect two wires at FREEZ STAT and jump them, compressor will run, again no cold, needs refrigerant.
Not very scientific but quick.
Use refrigerant gauges to verify charge of refrigerant in system. 
Gary B  ( AND, Wear glasses and keep your face away from charge ports and hoses, cold refrigerant in your eyes can be catastrophic ). :-(
Gary B

Re: U225 Dash Heater/AC Fan Quit

Reply #7 –
Craig,  I was very lucky, when at FOT, requested A/C repair, they brought a man up from the lower assembly plant, who does the dash heat & A/C system check out, he has been doing that for the past 22 years, was interesting watching him, took about 45 seconds, he had the bottom panels off, removed the BCM, Smart wheel modules and something else,  then had the relay with the wire that had worked it way off, he simply reattached with a better crimp on slide on connector, then secured it.  Bingo all fixed, I asked about the A/C on defrost mode, he said it was already setup for the compressor to be on with the defroster, OPPS!!, I said no it aint, then he showed me the correct position of the selector switch, if you go all the way to defrost the A/C is not on, but if you back up one notch, it is defrost with A/C on, OH ! I now get it.  Always nice to work with someone who knows what they are doing. Dash A/C since has been great since, Charge for that was 1 hour.  Very fair price indeed for the education alone on where that relay is burried, Geez.
Dave M

Re: U225 Dash Heater/AC Fan Quit

Reply #8 –
Only 1 thing runs the dash fan and that is 12V. No sense chasing AC problems if only the fan quit. It is located under the dash on the pass side. Enclosed in a casing, but the 12v connector will be looking at you, sort of.
1994 U280, Build 4490
Deming, NM.

Re: U225 Dash Heater/AC Fan Quit

Reply #9 –
There seem to be a variety of "fans" being discussed here.

Some are talking about the dash HVAC fan that blows air out the vents.  It may be inoperable or, if there is a problem with the vacuum pump or system, it could be stuck in its default position of defrost vents. This fan is accessible on the passenger's  under-dash area.

Others are talking about is the condenser fan, located in the "nose" and controlled by the A/C system and its relays.  There is also a resettable breaker that powers the fans and it may be bad as well.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: U225 Dash Heater/AC Fan Quit

Reply #10 –
Quote from: wolfe10 –
There seem to be a variety of "fans" being discussed here.

Some are talking about the dash HVAC fan that blows air out the vents.  It may be inoperable or, if there is a problem with the vacuum pump or system, it could be stuck in its default position of defrost vents. This fan is accessible on the passenger's  under-dash area.

Others are talking about is the condenser fan, located in the "nose" and controlled by the A/C system and its relays.  There is also a resettable breaker that powers the fans and it may be bad as well.

Brett

Yes... I saw the breaker on the wiring diagram and I assume that it's one of those located against the forward bulkhead of the battery bay. Just had all that apart for the inverter installation so I'll get in there again. Have to work on Hailey's bicycle anyway (someone adjusted the brakes so they rub on the rim of the rear wheel).

I think I'll start with that fan on the passenger side and see if it has 12vdc. I checked for air flowing through the defroster vents and there is nothing... also no sound at all from the fan (which I could hear when it was running).

Who needs a job when you own a 20-year-old RV?  :D

Thanks for all the input. :)

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: U225 Dash Heater/AC Fan Quit

Reply #11 –
Quote from: wa_desert_rat –

Who needs a job when you own a 20-year-old RV?  :D

Thanks for all the input. :)

Craig

Actually, after you get everything straightened out, you will find it is at least as reliable as most coaches 1/3 it's age. Partly because it has far simpler systems, partly because of the build quality.

But you are right-- if a 20 years old coach is not maintained and upgraded, it can keep you in a hobby.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: U225 Dash Heater/AC Fan Quit

Reply #12 –
Craig, I am 90% sure it is the relay that Gary first mentioned behind the driver rear wheels on the isolator/boost switch panel. It is in the wide open. Stick your head under the coach behind the rear wheels and you will see two, I think, brown plastic relays. One is for the dash air conditioner. If it is not functional, neither the condenser fans nor the blower fan will work. I'm betting it is simply a loose wire.

Good Luck!!!
The selected media item is not currently available.Kent Speers
Locust Grove, OK
1993 U300 SSE 40' (Restored at FOT 2009) Build 4323
720 watts Solar
6V92TA DDEC Silver Engine
2014 Subaru Outback

Re: U225 Dash Heater/AC Fan Quit - SOLVED

Reply #13 –
The problem was in the fan... or, rather, in the power connector to the fan. The black (ground) connects to the fan shroud by a self-tapping screw with a tongue-connector on it. The screw had worked itself loose and was wobblilng around. Simply tightening the screw fixed the problem. Dash fan works just fine. I'll check the function of the dash A/C next time we go out.

Thanks for all the help... much appreciated!

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."