ADDING AN ELECTRIC AUXILIARY FAN TO RADIATOR STACK ON ’03 ALPINE COACH

The original design of the ’03 Alpine Coaches (and perhaps other years as well) did not include any kind of engine fan engage mechanism to engage the fan when the dash air conditioning is turned on. The result of this is that the a/c system is prone to failure due to high temperature/pressure buildup in the system whenever the engine temperature is not sufficient to engage the engine fan.

The reason for dash a/c failure and/or inefficiency in my unit was originally diagnosed by my local diesel shop when I had two dash a/c system failures within a 2 month period. The diesel shop manager seemed familiar with the problem inherent to Alpine coaches and his recommended “fix” was to simply plug the wax valve bypass line which allows the hydraulic fluid to “bypass” the engine fan and flow back to the reservoir until the wax valve heats to the point of engaging the engine fan. This “fix” causes the engine fan to engage and run whenever the engine is running. This “fix” did resolve the problem of not having the engine fan kick on when the dash a/c was engaged because the engine fan ran all the time that the engine was running. However, I was not happy with the idea of having the engine fan engaged 100% of the time that the engine is running and decided there must be a better way to resolve the problem.

I had heard of another solution that involved installing a kit that involved installing a second valve in the engine fan bypass line that would engage the engine fan whenever the dash a/c was engaged. But, in my mind, I felt that any alterations to the engine fan operation isn’t the best solution to the problem.

That’s when I came up with the idea of adding an electric fan to the radiator stack that would engage whenever the dash a/c is engaged and would be “off” when not needed. The real challenge to do this is the lack of clearance between the radiator stack and the louvered body panel – and/or the lack of clearance between the a/c condenser and the intercooler radiator that does not allow the addition of a fan either on the exterior of the condenser or between the condenser and intercooler radiator. When I originally measured the clearance between the a/c condenser and the body panel, I measured just slightly more than 2 inches. I then found an electric cooling fan on Ebay that was only 2.5” in thickness. So, I purchased the fan, evacuated the a/c charge from the system, removed the a/c condenser from the stack, mounted the fan on the outside of the condenser using the provided hardware and then reinstalled the condenser on the stack. When I attempted to place the body panel back in place, lo and behold, it lacked about 3/8 inch of closing due to the raised reinforcing braces on the louvers. So, it was back to the drawing board.

I again removed the a/c condenser from the stack and determined that if the condenser could be moved closer to the intercooler radiator that it would provide enough clearance to mount the electric fan (as a pusher fan) on the outside of the condenser and have sufficient clearance for the body panel to clear. I finally ended up removing the condenser from the mounting brackets by drilling out the rivets that attach the brackets to the condenser. I then cut some 7/16” spacers from 3/8” rigid plastic tubing and inserted those between the mounting brackets and the condenser and reattached the brackets to the condenser using #10 x 1” metal screws. As stated previously, the electric fan was mounted to the a/c condenser using the plastic mounting studs that came with the fan by inserting the studs through the fins in the condenser from the back side (using the supplied foam cushions between the plastic studs and the condenser surface) then attaching the fan onto the studs on the front side of the condenser making sure the fan was securely attached flat against the condenser fins.

I then remounted the condenser unit to the stack which placed the condenser snug up against the intercooler radiator with no clearance between them. Note: There seems to be no valid reason that there needs to be clearance between the condenser and the intercooler radiator other than to avoid wear and so long as everything is mounted firmly, this should not be an issue. After moving the condenser closer to the intercooler radiator and installing the fan in this manner, there was sufficient clearance to replace the body panel.

Now for the electronics. I purchased a “Bosch” style automotive relay to handle the job of engaging the electric fan when the a/c compressor is engaged. I mounted the relay on the outside of and toward the rear of the fan shroud. I then tapped into the a/c compressor wire and ran a wire to the relay so that the relay engages when the a/c compressor receives power. Using this method does not require the addition of a fuse between the compressor wire and the fan relay because the a/c compressor fuse handles that task. I then ran a “hot” wire directly from the chassis batteries to the fan relay and then to the fan with a 15 amp fuse in the line to prevent damage due to fan failure or overload. I installed a ground wire from the frame to the fan shroud and grounded the negative side of the relay and fan wires to the shroud. With all wiring in place, the electric fan now engages whenever the a/c compressor engages.

STEP BY STEP INSTRUCTIONS

1) Open the louvered body panel in front of the radiator stack by removing the two bolts that secure it to the fan shroud and one at the rear that secures the panel to the body frame.

2) Open the body panel and either use a prop to hold it open, or remove it entirely by pushing it in toward the engine while holding the panel in a completely horizontal position. Note: When opening the body panel, be careful not to let the panel slip out of the upper mounting slot as this could cause damage to the panel and/or personal injury.

3) Evacuate the charge in the a/c system. (Note: It may be possible to make this modification without evacuating the system, but it was done by the author after evacuating the system and will be much easier if the system is evacuated and you can completely remove the condenser unit from the radiator stack.)

4) If you have evacuated the system, disconnect the two hoses from the upper left side of the condenser. If you have not evacuated the system, skip this step. (Note: Once you have completely loosened the threaded fittings, it may take a little effort to remove the hoses as they are tightly fitted in the fixture and the ‘O’ rings may have adhered to both surfaces. It is recommended that if you do disconnect the hoses from the condenser that you replace the ‘O’ rings upon reassembly.)

5) Remove the condenser from the radiator stack by removing the mounting bolts at the top and bottom of the mounting brackets. (Note: You may need to pry up on the top of the shroud just above the upper mounting bolts in order to get enough clearance to remove the bolts.)

6) Drill out and remove the 3 rivets on each side that attach the mounting bracket to the condenser unit to remove the brackets from the condenser.

7) Cut 6 (six) 7/16” pieces from a piece of 3/8” i.d. rigid plastic tubing (or any similar material). These pieces will be used as spacers when reinstalling the condenser unit onto the radiator stack.

8) Attach the electric fan to the outer surface of the condenser unit using the plastic mounting studs that come with the fan using the following sequence: (This step is much easier accomplished with the condenser unit completely removed from the hoses and brackets but is still possible to do with the unit still attached to the hoses.)

a) Position the fan on the condenser unit approximately centered horizontally and approximately 1” from the top vertically.

b) Using an awl, nail set, small Phillips head screwdriver or similar tool, insert the tool through the holes in the mounting tabs on the fan to start a hole in the condenser fins where the plastic mounting studs that come with the fan will be inserted. BE CAREFUL NOT TO PUNCTURE ANY OF THE TUBES INSIDE THE CONDENSER UNIT!

c) Set the fan aside and using the plastic mounting studs, locate the ‘starter holes” on the front side condenser fins and force the studs completely through the fins so they exit the other side. (Note: There are sections of the condenser where there are slightly larger spaces between the tubes. This is the area where you will want to route the mounting studs.)

d) Before removing the studs, mark their location on the back side of the condenser using pieces of tape or some similar method. (Note: If you don’t mark their location, it may be difficult to find the hole after the studs have been removed.)

e) Remove the studs from the front side of the condenser and install the cushioned foam pads on the stud side (what will be the side that goes against the condenser surface) of the retainer tab of the studs.

f) Reinsert the studs through the holes in the condenser fins from the back side of the unit.

g) Place a cushioned foam tab on the front side of each mounting tab so that when the fan is mounted in place, the foam tab will be between the fan mounting tabs and the condenser fins.

h) Install the fan onto the studs by slipping each stud through the mounting tab holes and the fan is snug up against the condenser fins.

i) Install the mounting stud retainers onto the studs with enough pressure to keep the fan securely in place against the condenser.

j) Cut the excess length from the studs leaving about 1” or so sticking out beyond the retainer tabs. (See Figure 2)

9) Now, reinstall the top of the condenser mounting brackets with the original bolts - leaving the bolts loose enough to maneuver the brackets. Do not install the bottom bolts yet.

10) With the fan securely in place, slide the condenser unit in behind the brackets and up into place.

11) Using the uppermost rivet holes in the bracket, place one 7/16” spacer between the condenser frame and the mounting bracket then secure in place by placing a 1” x #10 screw

through the hole in the mounting bracket and through the spacer and then screwing the screw into the original rivet hole in the condenser frame. Tighten only until snug so as not to strip the hole out with the screw. (See Figure 1)

12) Once the condenser unit is secured to the upper rivet holes in the mounting brackets, reattach the bottom of each mounting bracket to the stack.

13) Repeat this process for each of the remaining 4 mounting bracket/condenser frame holes. (Note: It may be necessary to slightly force the spacers between the mounting brackets and the condenser frame.)

14) Once the condenser is securely mounted to the mounting brackets, tighten all screws snugly (being careful not to strip them from the holes) and tighten the mounting bracket bolts securely. (See Figure 2)

15) Now, close the louvered body panel to ensure that it will close tight against the fan shroud. If it does not, it may be necessary to use slightly longer spacers between the condenser mounting bracket and the condenser frame to move the unit closer to the intercooler radiator. Or, it may be necessary to move the fan slightly higher or lower so that the middle inner louver support clears the motor shaft button on the rear of the fan housing.

16) Once you have determined that the body panel will close properly, open the body panel again and mount the fan relay toward the rear of the fan shroud. Leave the mounting screw loose as it will need to be removed to attach the ground wires later. (See Figure 3)

17) Drill a hole (large enough to accommodate a grommet & three wires) in the upper right corner of the shroud. Install a rubber grommet into the hole to prevent shorting of wires that you will run through the hole. (Note: The author drilled a 5/8” hole in the shroud and then inserted a piece of ½” rubber heater hose through the hole to insulate the wires from the shroud.)

18) To ensure that there is a proper ground for the fan and relay wiring, using a minimum #14 gauge wire, attach one end of the wire to the frame somewhere behind the fan shroud, then route the wire through the hole in the shroud and attach it to the shroud using the attaching screw for the fan relay. (See Figure 3.)

19) Now locate the a/c compressor wire that attaches to the top of the a/c compressor on the upper rear of the engine. Disconnect the wire connector from the compressor and tap into the compressor wire (using either a quick wire tap connector or by cutting the wire and installing a double ended butt connector) with a minimum #16 gauge wire. Reattach the wire connector to the a/c compressor and then route the newly attached wire over to and through the hole in the shroud.

20) Determine which of the terminals on the fan relay activate the relay. This information should either be included with the relay or will be shown in a diagram on the relay body. (Note: On the relay the author used, the two smaller gauge black & white wires are the wires that activate the fan.) Now, connect the wire you ran from the a/c compressor to one of the wires on the relay connector that activates the relay. Use a double ended butt connector to do this. This will be the +12 volt connection needed to activate the relay when the dash a/c is turned on.

21) Attach another #16 gauge wire to the other wire on the fan relay connector that is the other wire that activates the relay. Connect this wire to the mounting screw for the relay. This will

be the ground wire that is needed to complete the circuit necessary to activate the relay when the dash a/c is turned on.

22) Now find a convenient spot in the battery compartment to connect a minimum #14 gauge wire to the positive side of the chassis batteries.

23) Before attaching the wire to the batteries, route the wire to the other side of the coach where it will be inserted through the hole in the upper right of the fan shroud. (Note: This wire should be securely attached to other wires, hoses or to the frame as it is routed from one side to the other to ensure that it will not rub a hole in the insulation and short out at some later time.)

24) Once this wire has been routed through the hole in the shroud, the insulation should be removed from the end to expose bare wires. Now attach the battery end of the wires to the chassis batteries.

25) Now, remove the insulation from the end of the wires coming from the fan unit. Use a “jumper wire” to attach one of the wires to a chassis ground (the mounting screw for the fan relay is a good location to find a food ground).

26) Now attach the other fan wire to the “hot” wire coming from the chassis batteries. This will activate the fan and cause it to run.

27) Now, determine whether the fan is “pushing” or “pulling” air. This can be done by dangling a small strip of paper next to the fan frame while the fan is running. If the paper is “pulled” toward the fan, the fan is “pushing the air through the radiator stack and this is the correct direction for the fan to turn. If the paper is “pushed” away from the fan, the fan is “pulling” air through the radiator stack and is turning the wrong direction for this application. If the fan is “pulling” air through the radiator stack. Reverse the ground/hot wire connections and ensure that the fan is pushing air through the stack.

28) Now, connect the fan wires to the fan relay. You will note that in addition to the two wires on the fan connector that activate the fan relay, there will be three additional wires that are larger gauge. One of these wires is the “common” wire for the relay output side, one is “on” until the relay is activated and the other is “off” until the relay is activated. Determine which wire is the one that is “off” until the relay is activated and connect an “in-line” fuze holder with a minimum 15 amp fuze to this wire using a double ended butt connector. (Note: On the relay the author used, the blue & yellow wires were used for this purpose.)

29) Now connect a minimum #14 gauge wire to the other end of the in-line fuse holder wire using a double ended butt connector and connect the other end of the wire to the ‘hot” fan wire using a double ended butt connector.

30) Connect a minimum #14 gauge wire to the remaining fan wire and route the other end to the mounting screw for the fan relay (ground).

31) Now, securely tighten the mounting screw for the fan relay.

32) Reattach the a/c system hoses to the condenser. (If you did not remove the hoses from the condenser to make this modification, check to make sure the fittings are tight at this point.)

33) Testing the Installation:

a) If you did not evacuate the a/c system before making this modification, you can now check to make sure all wiring is working properly by turning the ignition system “on’ and engaging or turning on the dash a/c. This should activate the relay and the fan should run.

b) If you did evacuate the a/c system before making this modification, it will be necessary to get the system charged before turning on the a/c system because there is a “low pressure switch” integrated into the system that will prevent the a/c compressor from engaging without there being sufficient pressure in the system for normal operation (to prevent damage to the compressor). Once the system is re-charged, test the installation as outlined in a) above.

34) You can now go back and place wires inside plastic wire looms and use cable ties and wire clamps as needed to “spruce up” the installation.

35) Reinstall the louvered body panel back in place being sure that the upper mounting tabs are securely affixed and that the mounting bolts are securely tightened.

Parts & Materials List:

1- Universal (push or pull) 16 inch 12 volt electric automotive cooling fan rated at 1,750 cfm with a maximum depth measurement of 2.5 inches (including mounting hardware). Purchased on Ebay for $32 including shipping.

1- Bosch style 12 volt 30/40 amp automotive relay. Purchased on Ebay for $3.99 including shipping.

1- Heavy duty in-line fuse holder. Purchased at O’Reilly Auto Parts for $3.49 plus tax.

1- Rubber grommet (size depends on the size of hole drilled in the fan shroud)

6- 7/16” spacers (the author cut these from a piece of 3/8” i.d. thick wall plastic tubing.

6’ 16 gauge (minimum) wire (to connect relay to a/c compressor & to ground).

12’ 14 gauge (minimum) wire (to connect fan to relay & to ground).

Misc. wire ties, electrical connectors, clamps, wire loom.

FIGURE 1

SPACERS INSTALLED

BETWEEN ,MOUNTING

BRACKET & CONDENSER

FRAME MOUNTING STUD IN

PLACE WITH RETAINER

INSTALLED (WITH EXCESS

STUD LENGTH CUT OFF)

FIGURE 2

FAN & CONDENSER

INSTALLED IN PLACE

ON RADIATOR STACK

FIGURE 3

FAN RELAY MOUNTING SCREW (USED FOR GROUDING POST)

UNUSED FAN RELAY WIRE

GROUND WIRE TO FRAME

HOT WIRE FROM CHASSIS BATTERIES

WIRE FROM A/C COMPRESSOR

FIGURE 4

FUSE HOLDER INSERTED INTO HOT WIRE TO FAN

FINAL INSTALLATION OVERVIEW

FIGURE 5

FIGURE 6