1971 4320 cab electrical issue

[Blade Breaker]

Hi
On my 4320 there is a cab and in the overhead there is a blower fan and wiper switch. A month ago these did not work. Traced the problem to a solenoid on the steering counsel under the cover on the left side. Replaced it and all was perfect for about 1 hour or 4-5 engine starts. Then the solenoid failed. Figured it was a bad part. Replaced this part 2 more times and the same thing is happening. Tried a heavy duty solenoid same problem.
OK I checked the amp draw from the blower motor and wiper. 5 to 8 amps seems normal.
Checked the failed solenoid and it will not trip when powered.
Any ideas on what could be frying the solenoids?

A few more things I should also mention.
The solenoid is activated when the key is turned on. A wire from the ignition switch to the control terminal on the solenoid. One wire only and the power stays on until you turn off the key.
This is the oem design and original part. One terminal on the solenoid.
12 volt system

Thanks

 

[Tx Jim]

I agree that the amperage draw shouldn't be too high. JD calls the device a relay not a solenoid but I don't know the difference in the nomenclature.
AH98337 Relay ADD 52.49 USD
Here's the spec's on the JD relay.

 

[Blade Breaker]

Interesting. The part I took out looked nothing like that. It was a metal round solenoid. Must have had some different windings or something special to it.

I will give that a try. Makes no difference to me what it looks like
.

 

[Tx Jim]

Did old relay resemble parts key #8 from a 4020? AR46334 Relay ADD 37.79 USD or from an A&I dealer A-AR54484 Relay - 30.82 US

 

[Blade Breaker]

Did old relay resemble parts key #8 from a 4020? AR46334 Relay ADD 37.79 USD or from an A&I dealer A-AR54484 Relay - 30.82 US

Yes that is what it looked like. Thank you very much!

 

[jd110]

The AH98337 is the one you want. The other solenoids are starter circuit relays. They are not designed to be engaged for extended periods of time. The windings quickly overheat when left on for more than a minute or two at a time.

 

[Tx Jim]

jd110
JD also utilized the AR46334 for accessories. Here's a parts photo for one used on early 4430 HFWD & cab accessories