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Topic: Haldex Heater (Read 527 times) previous topic - next topic

Haldex Heater

I can't remember at what temp the Haldex heater comes on.

Anyone?

Re: Haldex Heater

Reply #1 –
Can't tell you the exact temperature, but all air dryers I have worked on have them.  The dryer would cease to function in below freezing temperatures (can't purge ICE) were it not for the heater.
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: Haldex Heater

Reply #2 –
I guess I can wait until the temp gets down around 32F and feel if it's warm with the ignition on.

Re: Haldex Heater

Reply #3 –
yes they are designed to come on once it senses freezing temps. There is a little button  temp sensor on the underside of the plastic part that sits in a recess in the bottom outside housing and "feels" the casting temperature. This is the "switch" for closing the circuit and applying the 12volts to heat.
One item I think that gets overlooked on the Pure Air model is the Turbo Valve. This should be changed as well and is part of one of the kits for major lower service DQ6026.
JohnH
Coachless, now use aircraft. 2003 Ford Travelair TC280 class C. Super shape. Just for 1 yr .
1994 Ford E350 ClassC,total renovation inside and out. Now sold.
2000 U295  36' Cummins 350 c/w Banks Stinger, Resonator upgrade,Solar, LED lites.Residential fridge with slide out pantry. Build 5674. Sold
ex 92 GV 022C ored Cummins. Sold
ex 95 GV240 cat 3116. Sold
2017 Mini cooper s & 2016 land Rover LR2 HSE  LUX.
jhaygarth@aol.com    SKP #130098
treat everyone as you would like to be.

Re: Haldex Heater

Reply #4 –
Quote from: John Haygarth –
yes they are designed to come on once it senses freezing temps. There is a little button  temp sensor on the underside of the plastic part that sits in a recess in the bottom outside housing and "feels" the casting temperature. This is the "switch" for closing the circuit and applying the 12volts to heat.
So is the heater on anytime the dryer casting temp is below freezing, or does heater only function with ignition switch "ON"?

If it is on anytime it freezes, this could be another "phantom" drain on the (start?) batteries.

But if it only works with ignition switch on, then the purge valve could potentially be frozen every time you start engine in below freezing temps.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Haldex Heater

Reply #5 –
Chuck,

Should be powered by an "ignition hot" source.  But, easy to confirm-- just unplug the pigtail from the dryer and check for voltage with ignition OFF and then ON.
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: Haldex Heater

Reply #6 –
Do as I say, not as I have done.

When receiving a new (rebuilt) unit check that it has a heater installed !

If not, use the old  heater, after checking with a 12 volt supply

CHECK AND INSTALL BEFORE MOUNTING THE UNIT !!!!!!!

very difficult to install after unit is in place.
1993 U300, 6v92
build 4366
USAF retired, Flight Engineer, C124, C130
 ATP, A & E.  & ex AI

Re: Haldex Heater

Reply #7 –
Chuck,

On the Unicoach (like up till at least '03) the heater is fed off a breaker that is hid in the breaker panel behind the kick panel just in front of the passengers seat.  It only has power when the key is on.  I don't recall the exact breaker # but it is shown on the B-2179 print.

I don't remember where the breaker is located in the Grand Villa's. 

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Haldex Heater

Reply #8 –
Quote from: Pamela & Mike –
On the Unicoach (like up till at least '03) the heater is fed off a breaker that is hid in the breaker panel behind the kick panel just in front of the passengers seat.  It only has power when the key is on.  I don't recall the exact breaker # but it is shown on the B-2179 print.

#16 on a 2003 U320.  Has white wire L3 running from it to the air dryer.  Not sure if it would be the same for a U295.
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320