HOW DO I ESTABLISH THE CAUSE OF FAULTY A/C CONTROLS?

  • Tiny
  • nissien
  • 1996 Isuzu Rodeo
  • 67,000 miles

I have replaced a faulty blower motor but am unable to power it. It appears to be an electrical fault, however on testing, fuses appear satisfactory. I wonder if there is a faulty relay.

1 Where is the relay situated which governs the air conditioning controls?
2 How do you remove the front panel where the A/C controls are positioned?
I removed 3 fixing screws but the panel remained firmly in position

Tuesday, January 10th, 2012 AT 5:38 PM

10 Answers

  • Tiny
  • Docfixit
  • Expert
  • 18,991 posts

Check Main fuse and blower fuse in relay box and find heater/ac relay. Do you have a meter or test light?

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Tuesday, January 10th, 2012 AT 5:51 PM
  • Tiny
  • nissien
  • Member

Thank you. Could you please advise how to remove the panel where the A/C controls are positioned?

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Tuesday, January 10th, 2012 AT 7:04 PM
  • Tiny
  • Docfixit
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Do not think that is problem do you have a meter?

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Tuesday, January 10th, 2012 AT 9:19 PM
  • Tiny
  • nissien
  • Member

Yes we have 12v meter, a continuity meter, and an ac meter incorporated and in addition a 12v test light.
The 4 speed a/c control is now faulty. The 3rd was previously faulty but the system was efficient.
Are you referring to the 100A Main or the ECM Main labelled EB-27?
We have checked relays EB- 21 (A/C COMP.) EB-29 (COND. FAN) and appear satisfactory.

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Tuesday, January 10th, 2012 AT 9:39 PM
  • Tiny
  • Docfixit
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ON blue/white wire to blower motor is there 12v+ when heater/AC on?

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Tuesday, January 10th, 2012 AT 10:01 PM
  • Tiny
  • nissien
  • Member

There was no voltage reading.

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Wednesday, January 11th, 2012 AT 12:11 AM
  • Tiny
  • Docfixit
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Check fuses underhood relay box
EB-16 100 Amp
EB-4 20Amp

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Wednesday, January 11th, 2012 AT 2:52 PM
  • Tiny
  • nissien
  • Member

I have returned. It is a 20 mile journey.
Fuses appear satisfactory.
There is no power to the blue/ white wire.
I have been told that the speed regulator/ resistor may be faulty. If that is so would that effect the power to the blue/white wire?

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Wednesday, January 11th, 2012 AT 5:46 PM
  • Tiny
  • Docfixit
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No blower resistor provides ground through fan switch to complete circuit. Was voltage checked at blower motor connector disconnected?

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Wednesday, January 11th, 2012 AT 6:25 PM
  • Tiny
  • Docfixit
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Also test fuses with meter looking not enough and need to know if power is feeding circuit

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Wednesday, January 11th, 2012 AT 6:45 PM

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