Question about A/C blower relay????

[pitbulldell]

On my 95 ex 4.0 every so often during the summer months when using the A/C wide open it will burn up the blower relay, i replace it and the fan blows fine the rest of the year. I replaced the blower because i thought it might have been going bad and pulling to much current through the relay and i cleaned all the connectors but again a few days ago the blower stopped working and sure enough the relay was burnt out. its the relay by the air filter box.What else should i check to stop this from happening

 

[budwich]

depends on what was "burnt up"... the operating coil OR the contacts???? IF its the coil then its in the control / heater switch domain... IF its the contacts, then something in the motor domain.

 

[pitbulldell]

depends on what was "burnt up"... the operating coil OR the contacts???? IF its the coil then its in the control / heater switch domain... IF its the contacts, then something in the motor domain.

Looks like the contacts are heating up and melting the relay.

 

[budwich]

"looks" are tough to "see" from across the internet... is the operating coil good? are the contacts "welded"??? metering would help with the "looks".

 

[pitbulldell]

"looks" are tough to "see" from across the internet... is the operating coil good? are the contacts "welded"??? metering would help with the "looks".

the bottom of the relay will be all burnt and melted and all the pins on the relay are discolored. the slot where the relay plugs into is a little burnt and discolored as well but thats just from the repeated heating up of the relays.I just dont know what could be causing the relays to heat up and go bad.

 

[budwich]

good description BUT you are probably "looking" at an electrical problem but you can't "see electricity".... as suggested, a meter will tell you (and us) something.

 

[pitbulldell]

good description BUT you are probably "looking" at an electrical problem but you can't "see electricity".... as suggested, a meter will tell you (and us) something.

I will check the voltage at the relay and at the fan and post the numbers.

 

[budwich]

You are looking for resistance and continuity. Continuity on the contacts and resistance of the coil. That will tell IF the contacts are "welded" (doubtful) and if the coil "burnt" open and / or is too "low" (causing heating)... likely. Of course, the last question is "is that the right relay for the application???" And lastly, just to be sure, which relay are you actually talking about as there are TWO involved assuming that you are talking about the manual system versus the EATC one.

I reread one of your responses... the one about the bottom of the relay "pins" being discolored. Not withstanding the above comments about the "internals" of the relay itself, if the "pins" on the relay are a problem, then it is likely their "receiver connections" in the box are dirty/oxidized... this may be causing a significant heat issue during use. Those contact points need to be cleaned and / or replaced...:-( Note: those aren't the contacts that I was initially referring which are the internal contacts of the relay itself (inside the "little relay box").

 

[pitbulldell]

thanks, after reading your last post I am gonna hit the junkyard tommoro and replaced the whole relay box.I will put the new relays in that one and see how it goes.