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Discussion Starter · #1 ·
Ok I know fans and wiring have been gone over ALOT, but, i have a problem.
I have 8 1991 mazda 626 lx atx car. I have engine, lighting, and transmission wiring from a 1988 mx-6 gt 5 speed.
When installing the wiring near p/s headlamp i noticed an interchangable harness going from pressure switches to relays and compressor clutch. The ac and fans worked correctly on the lx auto so i kept the same stuff there.
the ac fans did not work at all on the mx6 but compressor did. (a/c sucked @ idle)
Now my a/c still works, the condenser fan comes on @ idle when pressure gets high. The main rad fan does not come on. it does when removing the spade @ thermostat housing. it also comes on when engine gets to temp and cycles.
I know the main rad fan should come on with the a/c, and the condenser fan when needed due to pressure.
There must be a relay or switch bad?
Where? 3 by comp on rad support?
1 on firewall?
near batt?
SICK of removing spade connector on hot days for max ac in city!!!!
please help
 

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I am not sure I understand. I can follow when the fans come on/off but not what wiring harness you have switched.

You have a 91 LX auto and used harnesses from a 88 GT 5sp?
 

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splice in a switch for the spade connector, so you can disconnect it electrically when needed :D ... or just figure out whats wrong, its up to you. I'm gonna splice in a switch in my 626 just in case..
 

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You set yourself up for trouble mixing 88-89 and 90-92 electrical systems. There were a number of changes that make these incompatible. Best thing to do when swapping in a new engine from a different year range is to use ALL of the sensors from the old (factory) engine. You should have kept 90-92 sensors, etc.

Most likely your problem is due to the fact that 88-89 and 90-92 cooling fan thermoswitches work COMPLETELY OPPOSITE. On the 88-89, the thermoswitch disconnects from ground to turn the fan on. On 90-92, the thermoswitch connects to ground to turn the fan on. Get the correct 90-92 thermoswitches installed on your 88 engine and you will be all good.
 

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Discussion Starter · #5 ·
only problem im having is the main rad fan does not come on when ac is switched on.
the thermo sensors and wiring are correct for 88-89
only thing that is 90-92 is pressure switches and relays on rad support below ac comp.
I had this same problem with my 88 mx-6. the car the wiring came from
In essence my car is 1991 626 lx with all engine and trans wiring from an 88 mx6 gt 5spd
 

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The a/c compressor will not cut on if the rad fan is not working , I know because I had that problem earlier in the year. I had a fried a/c harness which had to be replaced and now all is well. You could also have a low or even high pressure issue with your a/c charge that will shut your a/c system down also.
 

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Discussion Starter · #7 ·
my comp. stays on its the main radiator fan. With only the condensor fan my high side pressure hits 225 psi. 54 degrees @ vent, unplug the spade connector @ thermostat, and turn rad fan on, 180 psi 32 degrees outta vents.
so i just unsure what relay must be defective or miswired due to my swap
 

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At the blue connector near the right headlight - Did you leave this on your car - Connected the end of the front harness from the turbo 88 to this blue connector?

You say there are 3 relays below the a/c?

If there are 3 they are as follows.

1 Normally open 20 amp for the a/c

2. NO for the a/c condensor fan. - Unsure of this as I think it is only there for a atx or turbo car. It turns on the condensor fan if the car gets hot enough. It can turn on without the a/c being on if the water temp get high enough.

3. NO relay for the rad fan to turn on when a/c is on.


Do not start the car but when it is cool work your hand down or up from under the car so you can touch the relays. Prior to doing this remove the black relay cover on the firewall. Find the one for the horn. With the key turned on have a friend honk the horn. You should feel the relay switching on when the horn is depressed and click off when button is released. You should now be able to tell by feel if a relay is working.

Then move back to the relays by the a/c. Feel each of these when the key is on and a/c depressed. Have friend cycle the a/c button. Find one that is not working. Tap the relay down with a long stick or pipe. Something to tap it gently off the clip. Remove the relay and then replace that relay with your horn relay. They are both the same. If the horn works then the relay is good. Look at the connector to see if there is a corrosion on the plug.

As MagiK has said there are difference in the way the cooling fans were wired. The 88-89 uses 3 relays down there and 3 diodes. From what you have said it looks like you have a a/c harness from a 88-89 turbo if you have 3 relays.

You can also remove the pressure sensor plug coming from the drier. Jump the 2 wires together so the condersor fan with stay on all the time the a/c is on. There are 2 pressure switches that are installed on the drier. One is the high pressure cut off and the one on the right is for the condensor fan. ( I think it is the right one when looking at the drier from front of car - or pointing to the Drivers side headlight.

This will help lower the condensor temps some. Works good if you have converted over to the new R-134.
 

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Discussion Starter · #10 · (Edited)
Ok this weekend im going to be replacing the front struts, along with ball joints again! I will check to see how many relays there are for sure, cuz ive had many f2t and f2 cars all models lol. i love em!!!
That harness or jumper harness you were describing with blue connectors, was wierd and has a diode as described.. was on my mx6 gt. The 626 has different one. All the relays on rad support lower are stock for 91 lx atx. main harness is 88 gt 5 spd. I have a new drier and all new o-rings full charge of r12.
Too bad i junked the mx6 due to rust.

Thanks a million ill keep ya posted
 

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The a/c wiring harness for a turbo car is different than a non turbo as it has more to it and even differs between a automatic and manual. The automatic a/c and cooling system are setup to handle more heat. If it all possible you need to get one setup as far as 88 to 89 and 90 to 92 and go from there, I really think it will help.
 
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