S175 no heat/blower motor

[Erockk]

Fan motor is not blowing

Has power at top left relay (hvac)
Has power at fuse to the left(hvac)

has no power at b terminal motor speed switch

i replaced motor switch (might be a coincident) but then fan blower worked

i moved the machine around and when i went to try switch again it didnt work

Need help where to check next

 

[frg]

check the connectivity between hvac relay pin 87 ,and B terminal on blower switch.

 

[Erockk]

check the connectivity between hvac relay pin 87 ,and B terminal on blower switch.

check continuity between relay and b terminal and all checked out ok. It almost seems like the relay isnt activating. Ive switched relays around but still same thing. Is there anyway to bypass relay? Im assuming could jump pins 30 and 87? But other then that i dont know where to look?

 

[Erockk]

Jumping pins 30 and 87 blower switch and blower work

 

[Erockk]

Also not getting power to bottom right 2 fuses, looks like say power plug and something unswitched

 

[frg]

check continuity between relay and b terminal and all checked out ok. It almost seems like the relay isnt activating. Ive switched relays around but still same thing. Is there anyway to bypass relay? Im assuming could jump pins 30 and 87? But other then that i dont know where to look?

HVAC relay, powered by SWITCH POWER relay. as soon as you power up the machin, the switch power relay energized and send voltage to Hvac relay. check the connection between switch power relay and hvac relay. also check the negative(-) terminal on hvac relay.
you can bypass this relay by connectin pin 30 to 87. but it drown you battery.

 

[Erockk]

HVAC relay, powered by SWITCH POWER relay. as soon as you power up the machin, the switch power relay energized and send voltage to Hvac relay. check the connection between switch power relay and hvac relay. also check the negative(-) terminal on hvac relay.
you can bypass this relay by connectin pin 30 to 87. but it drown you battery.

Ive been looking at wiring diagrams and i came to that conclusion too. I checked continuity between pin 87 on switch relay and 86 on hvac I got nothing. Ive noticed wiper switch has no power too, assuming it is coming from same source the switch power relay. Assuming pin 87 loose in fuse panel. Will check that out tomorrow

 

[Coaldust]

Winter is coming!. Gotta get that heater working, post haste. BTW, that’s some solid troubleshooting. Keep up the good work.

 

[Erockk]

Winter is coming!. Gotta get that heater working, post haste. BTW, that’s some solid troubleshooting. Keep up the good work.

woke up this morning to a dome light on and heat and wipers working. Cant make this up. But then again did clean all engine grounds and push the back of the fuse box boot to try and trace a 21-03 which just pop up yesterday for glow plugs. These electrical problems are a pain. Going to have to pull that fuse boot again and cause another random problem. Atleast can put interior back together knowing isnt a problem from above headliner

 

[Erockk]

21-03 turned out to be a bad relay from me switching them around. Found out 3 relays are bad. Thanks all for help looks like ive figured out the bad electrical on this neglected machine for now

 

[Coaldust]

Excellent!