Mechanics

RELAY PROBLEMS

Ford F-150

I have a 99 f-150 pickup it has about 93,000 miles on it the problem I am having is the blower fan for the air conditioner went out one day while I had it on high and the check engine light came on. I replaced the relay and the blower started working again but I had the air on high again and the relay burn out again the check engine light has stayed on the entire time. My question is would the mass air flow sensor cause the relay to go out?
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Denae
June 15, 2006.



Mass airflow sensor has nothing to do with your blower motor, take your truck to a parts store where they will read your codes for free, make sure you write the code down correctly, then post the code back here. As per my other posts, I recommend you spend a little money on an obdII reader, best investment you can do, will point you in the right direction, can be had for 100 bucks or less, can't do much without having some info.

Tiny
TaurusWheel
Jun 15, 2006.
I did get codes from auto store they were two codes PO171 and PO174 which lead me to mass air flow sensor and oxygen sensor and two or three other things it could be.

Tiny
Denae
Jun 17, 2006.
Those codes have to do with fuel trim problems concerning both bank 1 and 2, related to o2 sensors and maf's, among other issues I would check the following: Check intake air system for leaks, obstructions and damage. Check the pcv system to make sure all is hooked up properly, check for any vacuum issues, broken lines etc. Check the maf sensor, I would remove it from the car, make sure electrical connectors are in good shape and clean. Look inside the maf, there's usually a screen in the horn, on some if you look carefully you can see the tiny resistor wires that monitor the air flow, some are accessible enough that you can GENTLY wipe them off with a qtip and alcohol, sometimes they get dirty, well not really dirty in the dirt sense, but a film-type coating. Could aso be egr-related, fuel pressure issues, or even the pcm if all other avenues have been diagnosed out, If no luck with any of the above, issue may require assistance of the dealer or other qualified people, some of the testing of this problem requires specialized equipment and knowledge. As for the other a\c related problems, I don't believe these have any relation to above issues, possibly the blower motor is drawing too many amps and damaging the relays, Do you have manual a\c or the eatc system? The eatc system has the capability of self-diagnosing a lot of it's own problems. On the manual system, it could be the blower switch itself, by relay I assume you mean the resistor bank?

Tiny
TaurusWheel
Jun 17, 2006.