Forgot more than I know

Friendly format provided to inquire about automotive a/c systems.
Archived Forum

Moderators: bohica2xo, Tim, JohnHere, Dougflas, HECAT

tbirdtbird
Posts: 34
Joined: Sat May 02, 2020 1:48 pm

Re: Forgot more than I know

Postby tbirdtbird » Wed Sep 02, 2020 9:23 am

That is some nasty crap on the OT.
Long thread, don't recall if comp ever failed, if so condenser may not have been changed out, which is a must.

As far as cooling, there will be others here that understand the wiring behind the condenser fan coming on.
BUT FOR ME PERSONALLY I would never run the comp without the fan coming on, NEVER. And we wire them all like this. Others will take me to task but part-time fans won't haul the freight. It sure cannot hurt anything!!
User avatar
JohnHere
Posts: 258
Joined: Sun May 13, 2018 10:20 am
Location: South Carolina Upstate - USA

Re: Forgot more than I know

Postby JohnHere » Wed Sep 02, 2020 11:13 am

The cause of the surging blower fan could be the relay, the blower motor itself, or faulty/corroded wiring someplace. I don't think the issue has anything to do with the blower resistor or refrigeration system. It just decided to rear its ugly head at this time for reasons not known. I would start by direct-wiring the blower motor to the battery as a test. If it still surges (it'll run at full speed), then you'll know it's a bad motor. If not, then it's on to more involved electrical troubleshooting.

The deposits on the OT screen suggest that there's still debris inside the system that wasn't eliminated with the first round of parts replacement. Its source could be the evaporator, which I think you said earlier wasn't flushed. It's a real pain, I know, but the evaporator and all other flush-able components will have to be removed, thoroughly solvent flushed, thoroughly dried, and reinstalled. The compressor should be flushed several times only with the appropriate PAG oil. You'll need to replace the accumulator again, too. You might also have questionable HPCO/LPCO switches. So I think I would replace them as well while the system is open.
bevis
Posts: 19
Joined: Thu Jul 30, 2020 12:00 pm

Re: Forgot more than I know

Postby bevis » Fri Sep 04, 2020 11:38 am

tbirdtbird wrote:That is some nasty crap on the OT.
Long thread, don't recall if comp ever failed, if so condenser may not have been changed out, which is a must.

As far as cooling, there will be others here that understand the wiring behind the condenser fan coming on.
BUT FOR ME PERSONALLY I would never run the comp without the fan coming on, NEVER. And we wire them all like this. Others will take me to task but part-time fans won't haul the freight. It sure cannot hurt anything!!




When I changed out the compressor 2 years ago ( 2000 ) miles ago, I changed out the condenser, OT, accumulator but did not flush the system.
bevis
Posts: 19
Joined: Thu Jul 30, 2020 12:00 pm

Re: Forgot more than I know

Postby bevis » Fri Sep 04, 2020 11:43 am

JohnHere wrote:The cause of the surging blower fan could be the relay, the blower motor itself, or faulty/corroded wiring someplace. I don't think the issue has anything to do with the blower resistor or refrigeration system. It just decided to rear its ugly head at this time for reasons not known. I would start by direct-wiring the blower motor to the battery as a test. If it still surges (it'll run at full speed), then you'll know it's a bad motor. If not, then it's on to more involved electrical troubleshooting.

The deposits on the OT screen suggest that there's still debris inside the system that wasn't eliminated with the first round of parts replacement. Its source could be the evaporator, which I think you said earlier wasn't flushed. It's a real pain, I know, but the evaporator and all other flush-able components will have to be removed, thoroughly solvent flushed, thoroughly dried, and reinstalled. The compressor should be flushed several times only with the appropriate PAG oil. You'll need to replace the accumulator again, too. You might also have questionable HPCO/LPCO switches. So I think I would replace them as well while the system is open.


I have been experiencing the mysterious Ford Focus alternator light intermittently that comes and goes and I caught it on once with a meter close to me and the alternator was putting over 14 volts to the battery. I don't know what the hell is up with that light unless its a connection or ground issue. And now I'm wondering if the regulator inside that alternator could be going crazy and jacking the voltage causing the blower surge. I drove it yesterday and it didn't do it. Im sure its going to be like most 12vdc wiring issues, a bad or loose ground somewhere.
Last edited by bevis on Fri Sep 04, 2020 1:15 pm, edited 1 time in total.
bevis
Posts: 19
Joined: Thu Jul 30, 2020 12:00 pm

Re: Forgot more than I know

Postby bevis » Fri Sep 04, 2020 11:46 am

I think my next mode of attack is going to replace the head pressure switch since it seems the system seems to under perform on hot days when a weak head switch would rear its ugly head. With those high ambients, I doubt the suction switch would be the issue.
tbirdtbird
Posts: 34
Joined: Sat May 02, 2020 1:48 pm

Re: Forgot more than I know

Postby tbirdtbird » Fri Sep 04, 2020 7:44 pm

If you have failing diodes you can easily run the voltage way over 14.
Have it tested
bevis
Posts: 19
Joined: Thu Jul 30, 2020 12:00 pm

Re: Forgot more than I know

Postby bevis » Fri Sep 18, 2020 6:05 pm

If you have failing diodes you can easily run the voltage way over 14.
Have it tested




Oh if it were only easy to get out. Its the absolute hardest to get to alternator I have ever seen.
I had to take the damn thing out from the bottom. Its real special the way they installed it from the factory.
Theres a stud sticking out of the side of the block that the alternator slid onto on the way down the assembly line.
Then at some point it gets mated to the body. So, you think its no big deal, just take off the nut from the stud and slide it off.
NOT A CHANCE... The damn alternator hits the firewall before it clears the stud and the stud aint budging in the block.
I had to remove the pass side motor mount and pick up that side of the motor with an engine hoist and push the motor forward
so the damn thing would clear the firewall. SWEET...NOT.. Then I had to move a steering link to get it to fall out the bottom.
Its clear that the engineers never intended for anyone to work on them. they were made to be disposable. If that alternator
is an issue again, I'm ready have it accidentally catch on fire and burn to the damn ground...!

Return to “Automotive Air Conditioning Forum”