1994 Q45 a/c fan high speed only

[j. p. penn]

1994 Q45 103,000 miles, a/c fan will operate fine on high speed, but cuts off on the three lower speeds. all works well except that the fan only runs on the high speed. Could this be the fan control amplifier? if so, does anyone have a cheap fix for it? thanks jppenn

[Infinitiguy19]

Yep its the darlington resistor AKA fan control amplifier.

You can repair (Resolder) it yourself or test your luck with a used one or buy a new one for $50 from Infiniti Of Scottsdale.

Welcome to NICO.

[j. p. penn]

Thanks. I would like to try the repair, but do not know the values for the resistance when checking. I read skibane's post and would like to follow, but his fan ran continously. Would his fix be the same for mine? I'll try scottsborro, for local dealer is talking 248.00 plus tax. thanks, jppenn

[Infinitiguy19]

I am sure the resitance value (If any?) will be in the service manual.

The problems he faced you can face because i remmber MoD (Minister of Doom) haveing that problem.

$250 for that??? Are the looking up the right part?

[j. p. penn]

The $248.00 plus price was from an infiniti on line dealer. checked local dealer and he quoted $128 and change, tax included. infiniti scottsdale is $64.43 plus 9.50 delivery, considerabely better than the rest. am going to try to repair original if i can find the parts local or on line without delivery charges eating up any savings.

anyone know good site to purchase the electrical parts? thanks jppenn

[Q451990]

http://www.mouser.com for electrical components.

I wonder if the part is the same for the J30? If so your Pull A Part has two of them showing on their web site. No Q45s unfortunately....

http://www.pullapart.com

Keep in mind that the fan amp. is cooled by air flow from the fan, so it's failure could be due to a fan motor problem. I would clean everything and disassemble the fan motor and clean it up with electrical contact cleaner if you're hearing any unusual noise from it.

Heath

[j. p. penn]

TRIED THE MOUSER SITE. THEY HAVE THE TRANSISTOR AND THERMAL CUT OUT FOR ABOUT $9. INCLUDING SHIPPING. PULL A PARTS DID NOT HAVE A VEHICLE NEAR ME, SO I'M GOING WITH THE MOUSER SITE, THANKS, JPPENN

MAYBE......

[Skibane]

TRIED THE MOUSER SITE. THEY HAVE THE TRANSISTOR AND THERMAL CUT OUT FOR ABOUT $9. INCLUDING SHIPPING. PULL A PARTS DID NOT HAVE A VEHICLE NEAR ME, SO I'M GOING WITH THE MOUSER SITE, THANKS, JPPENN

MAYBE......

If you're considering ordering a FDH5500 MOSFET from Mouser to replace the original transistor in your Fan Control Amp, it won't work on pre-1997 Q45's. The Fan Control Amp on your G50 is different from the fan amp on Y33's. G50's use a Fan Control Amp with a Darlington bipolar transistor; Y33's use a Fan Control Amp with a MOSFET instead.

The 2SD1297 Darlington transistor originally used in G50's is apparently no longer in production, and is difficult to cross-reference to a different transistor that is still in production. However, you may be able to find a few of them in stock by Googling "2SD1297". I managed to find and buy 5 of them, 4 of which I'll be happy to sell to NICO members, at actual cost.

j. p. penn, the fact that your fan still runs at full speed (but can still be turned on and off with the A/C switch) is a clue that your problem may be something other than the Fan Control Amp. Generally, when the FCA fails, you either get no fan operation at all, or the fan runs at full speed for as long as the ignition switch is turned on (neither of which seems to describe what you're experiencing).

I hope to have an update to the "How To Fix Your Fan Amp" thread this weekend, which will also include the G50 version.

[j. p. penn]

SKIBANE:I DO NOT UNDERSTAND MUCH ABOUT HOW THE FCA WORKS, BUT JUMPED INTO TRYING TO REPAIR IT. IF THE REPAIR DOES NOT WORK, $75 WILL REPLACE THE FCA, HOWEVER; AS YOU STATED, THE FCA MAY NOT BE THE PROBLEM. BEFORE TAKING THE FCA APART, I CHECKED AND FOUND A DEAD GROUND BETWEEN THE BODY OF THE FCA AND THE PIN TO THE BLOWER MOTOR. THAT SOUNDS BROKEN, FOR AS I UNDERSTAND IT, THAT WOULD ALLOW THE BLOWER TO RUN HIGH WHEN TURNED ON. THAT BEING THE CASE, SHOULD NOT HE BLOWER RUN HIGH WHEN ON SPEEDS 1,2,OR 3? IN MY CASE THE BLOWER DID NOT RUN AT THOSE SPEEDS, ONLY 4 (HIGH).

AFTER GETTING THE FCA APART, I FOUND THAT THERE WAS "SOOT" OR SMOKED STAINS ON THE PAPER INSULATOR BETWEEN THE BOARD AND THE TRANSISTOR. ALSO THE TRANSISTOR WAS CRACKED. SOMETHING HAPPENED IN THERE. THE TRANSISTOR WAS LABELED "NEC D1297 J2X".WISH I HAD READ YOUR THREAD EARLIER FOR I JUST ORDERED THE FDH5500 TRANSISTOR THIS AM, WHICH YOU SAY WILL NOT WORK. SINCE THEN, HAVE LOOKED BUT CAN NOT FIND A CROSS REFERENCE FOR A CURRENT PART TO REPLACE THE D1297. MAY WANT TO SEE ABOUT GETTING ONE FROM YOU.

HAS ANYONE ELSE HAD A SIMILAR FAN SPEED PROBLEM? ANY HELP WILL BE APPRECIATED. I'M GOING TO FOOL WITH THIS FOR A WHILE BEFORE I BREAK DOWN AND ORDER A NEW FCA. THANKS, JPPENN

[jltibbs]

I bought my blower motor resistor for $70 at my local dealer. Problem solved.

By the way,

[j. p. penn]

$70 SEEMS OK AT SOME DEALERS, BUT OUR LOCAL GUYS WILL NOT TOUCH IT FOR THAT. BY THE WAY, WHAT WAS YOUR PROBLEM THAT WAS SOLVED? JPPENN

[maxnix]

By the way,

Since you seem to miss subtlety

IT IS RUDE TO SHOUT IN CAPITAL LETTERS!

Does that help?

[jltibbs]

$70 SEEMS OK AT SOME DEALERS, BUT OUR LOCAL GUYS WILL NOT TOUCH IT FOR THAT. BY THE WAY, WHAT WAS YOUR PROBLEM THAT WAS SOLVED? JPPENN

I, uh, had the exact some problem you are experiencing. You should be able to purchase the Resistor for no more than $70, and you can replace it yourself in thirty minutes or less.

Also I would take your keyboard to a local PC shop and have them fix your caps lock button.

[WesQ]

A few hours after I read this thread I took my 94 Q out for a ride and the HVAC fan went full speed. Just as described, the fan runs full speed as soon as the ignition is turned on. It continues at high speed no matter what button is pushed or word spoken to the AC/heater system.

I removed the FCA and hope to repair it myself. Skibane, do you still have a spare Darlington I could buy from you?

[j. p. penn]

SKIBANE:Got my fan control amplifier re-built and installed. Your 8/13/09 post, "problem may be something other than the fca" seems correct. Fan still runs ONLY when unit is on and then at high speed only. The fan does not run on the lower three speeds.

Has anyone else out there had this specific problem? Any suggestions, or where to find more information that a novice can understand. Thanks, jppenn

[Q45tech]

We keep spare HVAC control units to substitute as a test.Very common failures on 90-93 less so on 94-96 but still on ocassion a few per year has been the average.

AT HOME: I have a 6 foot double door cabinet FULL of electronic modules found in my 1990 at least 2 of everything for the future. At least $15,000 MSRP worth of goodies from ebay, wrecks and junkers over the years.

When I need a brand new CAS in stock and a used spare. Then I attempt a clean and repair just in case.

Some things like the HVAC fan controller are so plentiful in junkers that it may not pay to spend the time vs even discounted brand new cost.

I allocate my spare time [overtime] at $40 per hour just as the technicans do, including driving to from and picking up parts.