Hydraulic Radiator Fan

[hax]

As soon as a I start my 2001 350 hp coach the hydraulic radiator fan starts to run. The AC is shut off. Does anyone know if this a problem? I don't think the fan should run until the engine warms up? Is it thermostat controlled? It sure causes a dust storm in these Alaska camp grounds. Thanks Jim

[hax]

As soon as a I start my 2001 350 hp coach the hydraulic radiator fan starts to run. The AC is shut off. Does anyone know if this a problem? I don't think the fan should run until the engine warms up? Is it thermostat controlled? It sure causes a dust storm in these Alaska camp grounds. Thanks Jim

[Wil Rathke]

It is thermostatically controlled. And you mentioned that the AC was off. Does it start at high speed and does it slow down after warm up? Does it ever stop?

[hax]

Thanks Will: The speed increases with engine rpm and as far as I can tell it never stops.

[VAGABONDMAN]

You might want to have it checked out! I had a '98 with the hydraulic fan motor and had a real chrisis because the motor had "shims" to control hydraulic pressure and they were improperly installed; accordingle, there was 10%too much perssure which caused the hydraulic pump to fail and it took out the air compressor as they were connected with a common shaft. The result was that I had no power assist for braking or steering while going 70 mph on the freeway over Snoqualmie pass!!! If the '01 has the same set up, you better be careful.

[EngineerMike]

On startup, idling, the fan should turn 800 rpm or so. If you turn on your dash AC, it should call for higher fan rpms (I'm fairly sure). So start up with your AC off, then w/someone you trust a fair amount in the cab, crawl under @ the back of coach so you can see the fan turn and have that very good friend switch on the AC. You should see the fan kick up in turns. At full idle without call for fan, the fan will turn but you can see individual blades as they whiz by; this is actually a problem indicating a bad fan controller. If you have the rpm differential on AC call for fan, I'd relax, sound like all is well. If you hear the transmission engage, you chose the wrong "friend" to assist

[Jeff_S]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by EngineerMike:
If you turn on your dash AC, it should call for higher fan rpms (I'm fairly sure). </div></BLOCKQUOTE>At least with our 2000, the AC has no control of the engine fan speed. (I also know of a 2002 that works the same as our 2000.) The fan is only controlled by the coolant temperature. I'm not sure if it runs on initial startup (cold engine), but the AC will NOT increase the RPM of the fan.

A search of the forum found these:

04 Dash AC notice

Dash A/C Fan Problem

I had the problem mentioned in the second thread above. The repair shop insisted that I install an electric fan that is directly controlled by the TRINARY switch (thru a relay). The Trinary switch also shuts off the compressor if the high side pressure is above 305psi (which can happen if no cooling of the condensor is available).

I will post a diagram of the ACME system (which should also get included in the Tech Library, along with other stuff I have.)

[Jeff_S]

The Trinary switch protects the system from both excessive high & low pressure, while also providing another output to control an electric fan (optional as shown with dashed lines in the diagram).

The Trinary switch can be found on the outside firewall from the generator compartment, just about in front of the driver. It is about the same size as an oil pressure switch and is mounted near the dryer canister. It has two connectors on it, one for the compressor control, and the other is unused (just hanging) which could control a fan.

p.s. If a copy of the diagram in its full resolution is needed, PM me.

[hax]

Thanks to all. Mike, I'll try that, an being that I've been gone so long and my life insurance isn't paid up, I'll have my wife turn on the AC. Jeff no real need for AC, we haven't seen a day over 65 since we left AZ.
Jim

[Jeff_S]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by hax:
Jeff no real need for A/C, we haven't seen a day over 65 since we left AZ.
Jim </div></BLOCKQUOTE>Well, we been using the heck out of the A/C here in AZ. Had 118 degrees the other day when we were out with the coach at Lake Mohave, south of Vegas. Almost have forgotten what 65 would feel like.

Jim, I'll send you an email and let you know when it's "safe" (cool enough) to come back home.

Jeff.

p.s. Jim, put a request in the Alpine Coach Forum Membership sticky post at the top of the forum to have one of the moderators add you as an "Alpine Coach Forum Member".