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2009 Radiator Fan Relay question

 
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  • 2 Post By rsrocket1
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Old 07 Apr 2016, 05:18 pm
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Default 2009 Radiator Fan Relay question

First of all, thanks so much to NitroPT.
He took the time to spend several hours yesterday going through my week old 2009 Cruiser from nose to tail and sharing his tremendous wealth of knowledge about this car. Lots of stuff to do to this car, but nothing fatal or out of the ordinary for a car with 87,000 miles.

Firs things first. I told him the car overheated the day before. He had me turn on the A/C and said the Low Speed Fan is not turning on, check the relay. Last night I got a new relay and put it in. Today, going into work, the temperature was cycling between 195 and 203. When I pulled into the parking lot, I turned on the A/C and the temp started climbing to 221 before I shut the engine off. Radiator coolant was trickling down the parking lot.

Before going to work, I took the old relay and applied 12V to pins 85 and 86 and was hearing the relay click on at about 8V and click off at about 5V. I also checked for continuity between 87 and 30 as the relay was turning on and it also functioned fine so the relay seemed OK.



At lunchtime, I did a little more testing. I put the old relay in the other socket, still no fan turn-on with the A/C at max. So it looks like the relays are good.

With the ignition on, but the engine not running, I measured the voltage between 87 and 30 on both sockets with the relays removed. On the high speed fan relay socket, I got +12 Volts. On the low speed fan relay socket, the voltage across the same pins measured 0 Volts. (Edit: That's probably because the fan has an open connection on the low speed side).

I then took a jumper and jumped the front and back terminals (87 and 30). On the high speed relay socket, the fan turned on when the pins were shorted. On the low speed relay socket, shorting the pins did nothing. On a whim, I then tried shorting the RETURN of the high speed relay socket to the +12V side of the low speed relay socket and the fan came on at the same speed as when I jumpered the pins on the other socket.



Finally, I measured the voltage across the coil terminals of the Low speed relay socket. It measured 0 Volts with the A/C off and 12 Volts with the A/C on.

Observations:
  1. The fan is not turning on when the A/C is turned on
  2. The fan does turn on and it seemingly has worked even at traffic stops
  3. The relays are good
  4. The windings and brushes on both low and high speed sections are good(?) <<--Not true, likely the low speed brush is probably not making contact with the commutator.
  5. The console temperature gauge is good (corresponds to OBDii temp reading)
  6. When the fan turns on, it effectively cools the engine (drops it down to 195F)
  7. The coil is getting 12 Volts when the A/C is turned on

This leads me to the conclusion that 12 Volts is not getting to the Low Speed Relay Socket. It looks like the schematic shows that the wire is simply "T"-ed from the power distribution center with 12 gauge wire. (Edit, I reversed the voltage measurement and it's likely that the return is not complete on the low side of the fan motor)

Edit, so now I'll just order a new fan assembly and remove the fan once and replace it with a new one. The old one was probably the original. This car has 87,000 miles on it and the fans often wear out by 50,000.

Thanks

Last edited by rsrocket1; 08 Apr 2016 at 12:12 am.
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Old 07 Apr 2016, 06:18 pm
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Default Re: 2009 Radiator Fan Relay question

Calling ya now

By the way I thought after I let you drive my PT you would be shopping for a GT Turbo PT Cruiser now?
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Old 07 Apr 2016, 11:58 pm
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Default Re: 2009 Radiator Fan Relay question

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Originally Posted by NitroPT View Post
Calling ya now

By the way I thought after I let you drive my PT you would be shopping for a GT Turbo PT Cruiser now?
That was an awesome ride and the acceleration was amazing. I never would have thought a PT cruiser would have that sort of get up and go.


Alas, as I was getting ready to do the bypass of the fan power, it looks like I made a mistake in measuring the voltages. It looks like pin 30 on the relay gets 12 Volts (as referenced against the jump start bolt on the front). Both sockets are connected to 12 Volts all the time. Sending 12 Volts from either the high speed relay socket or low speed relay socket into pin 87 of the high speed relay socket makes the fan run. Putting 12 Volts from either into the Low Speed relay socket does nothing.

So it very well might be a bad low speed brush on the fan motor.

It doesn't look to difficult to replace the entire fan assembly. Just remove the grille, engine compartment gasket, disconnect the radiator top hose, remove the metal cover over the top of the radiator, then 6 bolts holding the fan assembly which then comes out from the top.

I'll edit the original post so as not to mislead anyone.

Oh well, another item to add to my Rock Auto shopping cart.
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Old 08 Apr 2016, 12:24 am
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Default Re: 2009 Radiator Fan Relay question

Quote:
Originally Posted by rsrocket1 View Post
That was an awesome ride and the acceleration was amazing. I never would have thought a PT cruiser would have that sort of get up and go.


Alas, as I was getting ready to do the bypass of the fan power, it looks like I made a mistake in measuring the voltages. It looks like pin 30 on the relay gets 12 Volts (as referenced against the jump start bolt on the front). Both sockets are connected to 12 Volts all the time. Sending 12 Volts from either the high speed relay socket or low speed relay socket into pin 87 of the high speed relay socket makes the fan run. Putting 12 Volts from either into the Low Speed relay socket does nothing.

So it very well might be a bad low speed brush on the fan motor.

It doesn't look to difficult to replace the entire fan assembly. Just remove the grille, engine compartment gasket, disconnect the radiator top hose, remove the metal cover over the top of the radiator, then 6 bolts holding the fan assembly which then comes out from the top.

I'll edit the original post so as not to mislead anyone.

Oh well, another item to add to my Rock Auto shopping cart.
Don't forget to first take out the battery and the battery support plate. This will help you with more clearance in getting the radiator fan out without damaging the radiator itself.
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Old 08 Apr 2016, 05:06 am
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Default Re: 2009 Radiator Fan Relay question

.....

Last edited by rckstein; 25 Apr 2016 at 11:59 pm. Reason: Removed because some other member wants to run the entire forum
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Old 08 Apr 2016, 09:00 am
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Default Re: 2009 Radiator Fan Relay question

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Originally Posted by rckstein View Post
A Goodyear shop recently replaced the cooling fan on my PT and didn't have to remove these items. I know so because while in the middle of the repair, I wanted to show them a missing fastener where a previous shop that replaced the fan had failed to put back in. When I went to the shop bay to show them the missing fastener, they had the old fan out and the battery and support plate were still in place in the vehicle. It might make it easier, but they did it without removing and didn't cause any damage.
I remove the battery support plate to keep from moving the radiator forward as much because of the strain its puts on all the lines going to the radiator. I don't like replacing any other components. Just the radiator fan component I am replacing!
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