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Fan keeps quitting
#1
When I first bought the RV the fan for heat and AC in the cab didn’t work.   It turned out to be a relay.  Replaced it...all was well.    Then about 2000 miles later..it stopped working.   Turned out to be that same relay.

So...another 2500 miles, and...yep...no fan again.  (Bummer in this heat).  AC works fine...just no fan.  As a temp measure, I mounted a little 12v fan to the vent....it helps.

I am guessing it is that relay again.   I’ll have a garage in NC look at it in a couple days.   Looking for ideas.  Why would the relay have to be constantly replaced?   It is mounted on the chassis in front, next to the radiator....not behind the engine where so many other electronics failed in the heat.  

Anyone else have issues like this?   1989 Ford E350.  460 engine.



1989 Honeywell motorhome
Ford E350 chassis.  460 engine
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  • American Nomad Patriot (06-12-2018)
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#2
Have you purchased all the relays from the same source?
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  • American Nomad Patriot (06-12-2018)
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#3
It might be an aftermarket part that is not made to any OEM standard, and if they are the same manufacturer, that may explain it. 

Can you easily replace it if you carried a spare?

Also, it might be the socket it plugs into...which may be corroded, causing heat, or loose connections after some vibration for a few thousand miles. 

Have them check all the pins in the socket, front and back.
Wondering about Wandering.
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  • American Nomad Patriot (06-12-2018)
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#4
Relays are simple electromagnets that open and cose contacts which carry much more current than a regular switch can.

But they also vary widely in quality, and price.

There is a standard size relay, usually referred to as a bosch relay, and Bosch does actually make this relay, but there are also dozens of other brands making 'bosch' style relays, One can find them 5 for 7$ where as the Bosch itself might be 23$ for one.

Some are sealed, some are not.

When the contacts open or close there is stresson the contacts as a spark jumps between. the actual contact material is very important in longevity.

Of equal importance is the connections at the relay, especially those carrying the load of the fan itself. If the connections for these 87a and 30 terminals are loose, it will cause issues to arise quickly no matter the quality of the relay.

also the connectins powering the fan itself, at the fan, can be highly resistive and causing the issue at the relays.

Basically any electrical connection is suspect. Either the relays are junk, or there is excessive resistance somewhere in the circuit feeding the fan. Changing out a relay is little harder than flipping a switch, but finding a connection with excessive resistance takes more effort.

a worn out motor can also consume a lot more juice than it should and overload the circuit powering it, and the weak spot could be the relay, and simply replacing it is a bandaid which will peel off in short order, and do so with more frequency as the motor continues to degrade.

Most mechanics will just slap a new relay in thee and stick their hands out. you need to find one willing to pursue the cause of the premature relay failure, and that is llikely a bad connection at the fan itself, and perhaps the fan itself, but could be anywhere along the circuit.
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  • American Nomad Patriot (06-12-2018), RoamingKat (06-12-2018), Scott7022 (06-13-2018)
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#5
Because most "mechanics" are just parts replacers these days.
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#6
(06-12-2018, 11:21 AM)ratfink56 Wrote: Because most "mechanics" are just parts replacers these days.

I agree with you there Rat. I was trying to track down a problem on one of trucks not shifting right. I told the shop manager up front that I wanted him to tell and show me what part is bad, broken,etc and why. Not to throw parts at it until it's fixed. If a part didn't fix it then to take it off and put old one back on. Well the shop threw 5 different parts at in that didn't fix it and had to replace with old original ones. After that they told me they had no idea what was wrong with it and to come pick it up. The list of parts they tried would have cost me $400. I paid them $30 bucks cash for their troubles (they didn't ask for it). Anyways, what you say held true at that shop.
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#7
(06-12-2018, 11:21 AM)ratfink56 Wrote: Because most "mechanics" are just parts replacers these days.

Oops ..hit the reply button twice. LOL
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#8
American...thanks for the detail answer. I need that level of knowledge to be able to figure this out. I will insist the shop I take it to show me and talk to me.

I had sort of wondered if it could be the fan motor itself is so old...it is “resisting” and drawing more amps than the relay was built to handle. But...wouldn’t that blow the fuse first? 15amp fuse I am sure.

But, clearly something is causing these failures. And..yes, I plan to buy 2. One to keep as spare...get the shop to teach me how to install it.



1989 Honeywell motorhome
Ford E350 chassis.  460 engine
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  • American Nomad Patriot (06-12-2018)
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#9
Most of those are visible. 

Use google for a motor component diagram for your beast. 

When I opened my fan I found mud dauber nest causing excessive power draw. You have the skills. I have seen your work.
Compared to parenting, Cat herding is less complicated 
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#10
(06-12-2018, 12:50 PM)GotSmart Wrote: Most of those are visible. 

Use google for a motor component diagram for your beast. 

When I opened my fan I found mud dauber nest causing excessive power draw. You have the skills. I have seen your work.

Yep...seen that too. Along with a rat nest (no relation to Mr, RatFink here) that caused problems as well.
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