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Old 02-26-2020, 11:17 AM   #1
Freightliner Owners Club
Join Date: Jan 2020
Posts: 40
Unhappy Fan motor/Resistor issue National 7370

Good morning guy & gals. Posted this to the Freightliner forum but no luck. Thought I'd try fellow owners. I have 2000 Nat'l 7370. A/C heater fuse blew. Checked with mechanic and he said the fan motor & resistor were drawing too much amperage. I ordered new fan & resistor parts and put them in. Started working and after 3-4 minutes on heater, the fuse blew. I replaced the 25 amp fuse and started it again on A/C - low and after 3-4 minutes, the fuse again blew.....ARGH!! Any ideas would be appreciated. Thanks.
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Old 02-26-2020, 12:28 PM   #2
Join Date: Sep 2006
Location: Texas
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It is most likely an Evans Tempcon system
Go here and find what your dash control looks like to find our more and troubleshooting info.
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Old 02-26-2020, 03:33 PM   #3
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Get a good amp meter and measure the draw. If greater than fuse size troubleshoot extra load.

If less than fuse size, the fuse is not blowing, but melting. Clean the connections or replace fuse holder.
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Old 02-27-2020, 09:55 AM   #4
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Angry ****UPDATE**** Please help!

Update on this issue. I pulled and rechecked the fan motor and connectors. I replaced the resistor with a another new one. Replaced the blown 25 amp fuse. I ran the unit on VENT at all speeds for 20 minutes without issue. Wires were cool.

I turned the dash controller to the right to CHEST/LEGS position and heard the relay activate. After about 30 seconds, I felt the green wire that runs from the 25 amp AC/HEATER fuse to the relay very hot. I shut it off before it blew the fuse again.

Could the relay cause this? Also, why does the relay activate on the CHEST/LEGS setting but not on the VENT setting? Any ideas on what I can do next?


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Old 02-27-2020, 10:25 AM   #5
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Here is the link to Evans Tempcon guides. Find your control type and download the electrical schematic. The dash lines typically are not supplied by Evans. One schematic I looked at shows the relay is for the condenser fan, if you have one.
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Old 05-31-2020, 10:32 AM   #6
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I do not know if you have this problem fixed or not.I own a 2000 7370 with a cat engine on a freightliner frame. I called my freightliner co. they claim it is a add on a/c from National. First check your a/c compressor mine was frozen up and clutch engaged all time. Second ck the fan on the condensor radiaton in front see if it has power I changed mine also then I replaced the evaporator on firewall. after all these repairs it works great now. with compressor freezing it pulled to many amps blowing fuse when you turned on a/c for air or heat.Hope you get it repaired.
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fan, national

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