Almost got this block heater in place and ready to go for winter.
But I would like the bunk heater to work in case I want to do some winter camping.

This link is for a different unit than mine, but it was the only refrance to my thermostat controller.

See page 9 - Unit 2 (D9W plumbed with an OEM heat exchanger.)

http://www.espar.com/documents/D9W.pdf

Where is the heater relay located? Is that referring to the blower relay that is located under the large plastic case in front of the fuse box?

welcome to the forum
sorry the site blocked your thread due to your being a new member and posting a link.
someone on here should point you to the relay.
more information on your car and what you are trying to heat may be needed.
is your car manual controls, or US version ACC?

__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

My car is the us version I think (im located in Canada)

It is a wagon aswell... I dont think that should change anything.

I have been taking pictures. if I get some time around Christmas ill show you what I did to install the webasto.

If I understand what you're trying to do, you're installing the aftermarket diesel-powered heater and you're trying to install it to also extract heat from the OE heater core in order to heat the 300TD in case you're going to camp/sleep in the wagon? Is that correct?

Page 15 describes the function, so you're looking to provide an auxiliary path of power to the blower?

I'd recommend caution since the blower motor is a high-current device and can draw excess current through the fuse box. There's an auxiliary fuse-box mod that was done by M-B to reduce the likelihood of melting the fuse box @ fuse 8, I believe.

Also, routing of airflow and clean, fresh air intake into the cabin via the OE ducting should be carefully planned and checked if your diesel powered block heater exhausts within the engine bay but you're using the OE heater core.

The link provides the schematics for airflow control, so that may be useful: http://www.peachparts.com/shopforum/general-information/295241-scans-airflow-w123-climate-control.html

Yes the heater is installed under my hood right behind my drivers side headlight.

My heater has a 20 Amp fuse the the wires on my relay are bigger than the blower cables, So I am not worried about drawing too much power.. this unit is made for semi trucks and large boats, which also have large blowers.

Also the unit wont draw any current through my fuse box as the espar is directly connected to my battery, and will supply power through the wiring harness to my thermostat control.



I am trying to find out the best place to cut in the relay (See page 9 - Unit 2 (D9W plumbed with an OEM heat exchanger.))

I am trying to find out if the relay im looking for is the relay on the drives side. under the big plastic box. The relay has a fuse built into it. Correct?

Also suggestions on following back wires would be appreciated.. I dont want to puncture a hundred cables trying to trace them around my dash.

Any help would be greatly appreciated.

I'm not entirely sure what/how the system you're installing controls, but I don't think there's a "heater relay" that replicates the function needed.

In your install, does the system energize the car's heater system, or just the blower on low speed?

The drawing on page 9 of your link looks like it recommends splicing in a changeover relay between the low-speed control (which is behind the glove box, I think) and the resistors. I think the resistors are on the passenger fender in the engine bay. That changeover relay would would use "car" power for low speed blower when the espar thermostat is not engaged, but use "espar" power when the thermostat is engaged.

I think the "heater relay and fuse" mentioned on page 9 to the right of the changeover relay refers to the espar relay and fuse contained in your kit, NOT one already in the car. If you look at the illustration and instructions on page 12 it points the black wire back to the espar box. This would seem to make sense with powering the car's blower and the thermostat via the espar unit and not via the car's wiring.

The relays under the black box on the DS fender are the A/C compressor relay and the aux fan relay. There may be others there, but I can't recall of the top of my head.

If (and that's a big IF) the above post is correct, and "Speed 1" output is the low speed you want from the M-B's system, and the fan speed controller is behind the glovebox and the resistors are on the right fender and the wiring diagram I'm looking at is correct for your car; then (and that's a qualified THEN) the wire you may want to splice the changeover relay into is a green/blue wire going from pin 8 on the controller to pin 5 on the resistor pack.

I'd double check all this with a meter, wait a few days to see if someone else chimes in, maybe start a specific thread "where are the blower resistors in 82 300TD" or "where is the blower controller" and maybe wait until Monday before splicing wires on your car. The Thanksgiving holiday weekend here may have taken some knowledgeable members off line for a few days.

Yes my car has the resistors on the passenger side, under the hood.
My blower relay that was supplied by espar, will be wired in close to the fuse box (Fuse #8) Where would be the easiest place to get to this wire? Is the fuse box easy to take out? seems like a sketchy place to work, being 30 year old wires and all.. It would be good to get in there though, my number 8 holder has already started to melt once before.

What is the Aux fan relay for anyway? is that the fan on my rad?