# 2005 Frontier air conditioning issue. Help!



## MJSchimpf (May 20, 2013)

So its summer time in Minnesota now and this ac issue I'm having is making me miserable on hot days.

My AC only works on the low setting, which is basically worthless when its real hot out. If I turn the knob to a higher setting, the cold air is very intermittent. The AC light will come on for random 5 minute intervals, then randomly turn off. When the AC light goes off, air continues to blow out the vents but becomes warm. As soon as the light randomly comes back on, the air is then ice cold again.

It always works on the low setting but intermittently on any setting higher than low.

I've been doing some Googling around, which led me to the Blower Motor Resistor. However, it seems when this is bad, the AC will only work on the highest setting. My issue is the opposite.

The other thing I saw was a fan switch. I'm hoping to fix this myself and save some money.

Anyone have any ideas? 

-Mike


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## smj999smj (Jan 1, 2006)

Not to confuse the actual vent output with the actual blower fan speed, if the fan speed is affected, it "could" be a fan switch, but, if not, I would check the AC system pressures with gauges to confirm the freon is not low. Not sure if it's related to your problem, but I found this TSB:

Reference: NTB09-028A

Date: November 17, 2010

LOW AIRFLOW FROM HVAC FRONT AIR VENTS

The Applied Vehicles have been amended. Please discard previous versions of this bulletin.
APPLIED VEHICLES:
2004-2008 Quest (V42)
2005-2011 Xterra (N50)
2005-2011 Pathfinder (R51)
2005-2011 Frontier (D40)
2004-2008 Titan (A60)
2004-2008 Armada (TA60)

IF YOU CONFIRM

An Applied Vehicle has low airflow coming from the HVAC front air vents due to evaporator freeze-up.

AND

The HVAC unit surface temperature around the evaporator is about 32°F (0°C) causing ice to form on the evaporator.

NOTE:
The incident may be described as:

^ Only occurring after a long drive with the HVAC on continuously and the blower set on low.

AND
^ Under conditions such as high ambient temperature and high humidity.

ACTION

^ Replace the intake sensor with the part listed in Parts Information.

^ Refer to the Service Procedure below.

SERVICE PROCEDURE
^ For Titan and Armada: follow the procedure outlined in this bulletin for intake sensor replacement.

^ For Quest, Xterra, Frontier and Pathfinder: refer to the appropriate section in the Electronic Service Manual (ESM) for intake sensor replacement.

1. Remove six bolts from the glove box.

2. Remove glove box. The intake sensor is located behind the glove box.

3. Disconnect the intake sensor electrical connector.

4. Remove the intake sensor by pulling it up and out from the front heater and cooling unit assy.

5. Install new intake sensor in reverse order of removal and connect the intake sensor electrical connector.

6. Install glove box in reverse order of removal.

PART: INTAKE SENSOR, P/N: 27700-ZC00A


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## MJSchimpf (May 20, 2013)

No. The air flow itseld is as expected for the level the AC knob is set to. Its the temperature of the air and the AC light that is the issue. I found on several forums that others with Frontiers and XTerras have replaces the Blower Motor Resisitor and it solved the issue. I just went ahead and ordered that part. As soon as it comes in I'll replace the old one and see what happens.

Thanks for the quick reply!


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## smj999smj (Jan 1, 2006)

I hope it does, but the blower resistor shouldn't have anything to do with the AC function nor the AC operation, other than the speed of the blower fan. The resistor is a series of paths on a card that route the ground path of the blower fan circuit. 12 volts is applied to the blower fan at all speeds. At max speed setting, the ground is routed directly to ground and the fan runs at full speed. At each speed setting other than max, the ground path is routed through a resistor that will cause the fan to run at a slower speed. The slowest setting is the path on the blower resistor that has the highest resistance, which causes the blower fan to run at its slowest speed. Where there is resistance in a circuit, there is heat, which is why they install the blower resistor in the path of the airflow out of the blower fan (to keep it cool). Usually when a blower resistor fails, it burns up at one of the resistors, usually leaving only the path directly to ground and letting the blower fan work only on the highest setting. Anyway, that's how it works. Keep us up to date and let us know if it fixes your problem!


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## MJSchimpf (May 20, 2013)

I will definitely keep you up to date. This just started happening a few weeks ago. I was able to deal with it because the weather was really cool and having the sunroof open was plenty of cool air. Now that its been in the 80s and 90s, it gets really hot after a while.

Odd, the ac worked great all day on Saturday when I was around town. Then Sunday acted up again and didn't work at all Sunday night. Again, when i say "didn't work", i mean the air flow was fine but it wasn't cool air.

Think its worth checking the freon level? When the ac light does manage to come on, the air is ice cold. Wouldn't that rule that out?


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## smj999smj (Jan 1, 2006)

If the freon is low (but not empty), it could intermittently cause the pressure to drop low enough to cause the low pressure switch to open the circuit to the AC compressor clutch, which would turn off the AC.


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## Cusser (Apr 16, 2004)

smj999smj said:


> I hope it does, but the blower resistor shouldn't have anything to do with the AC function nor the AC operation, other than the speed of the blower fan.


But it does, the circuit grounds through the blower resistor, and on my Mazda B2200 truck, too.


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## smj999smj (Jan 1, 2006)

The blower fan circuit grounds through the blower resistor on the Frontier, but the AC doesn't. The front blower motor relay provides the power to the blower motor. The ground circuit of the blower motor goes through the blower resistor, then through the fan speed switch to ground. The different positions of the fan switch determine which path the current will flow through the resistor. The AC compressor clutch is actually provided power by the AC relay in the IPDM/ER. This is controlled by the CPU of the IPDM/ER, which communicates with the ECM. The ECM gets a direct input from the pressure sensor. The ECM also communicates with the BCM, which communicates with the front air control, which operates the mode doors, receives input from the intake sensor, and outputs to the defogger and illumination systems. We have to remember this isn't the AC system used in the good ol' days; it uses CAN (Controlled Area Networking) which is why it's hard to diagnose problems on these systems without a capable scantool. All you can really do if you don't possess a scantool is check the basics. If that doesn't work, it's off to the repair shop!


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## MJSchimpf (May 20, 2013)

I am happy to report that replacing the Blower Motor resistor fixed my issue! AC works great now and only took 5 mins to replace!


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## Wickedpski (Jul 25, 2016)

I would like to thank everyone on this post. I have a 2005 Pathfinder. The A/C only worked on the lowest setting (1). 2,3,4 would blow air but the A/C light would go out and hot air blew in. While on setting 1 the A/C light came on and when I turned up the fan speed cold air would blow out for a few seconds. The A/C light never came on while the blower was in 2,3,4. 
So after reading that it could be the Blower Fan Resistor Board I went out and bought one. Unfortunately the only video I found on the replacement showed pulling out the glovebox. Ooppps, that was a waste of time. The resistor can be reached by reaching under the glovebox and to the left of the blower motor and towards the firewall. It's the only wire in that area. So now I'm nice and cold again.


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## H20HI (Aug 18, 2016)

My AC works well when my frontier travels on high speed such as on the freeway, but then when I drive in traffic the AC stops working and also my Temperature gauge peak at max high.


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## Cusser (Apr 16, 2004)

H20HI said:


> My AC works well when my frontier travels on high speed such as on the freeway, but then when I drive in traffic the AC stops working and also my Temperature gauge peak at max high.


These are CLASSIC symptoms of a bad fan clutch (if your truck has this) or bad electric engine fan operation (if your truck has this). When you drive at higher speeds, air is rammed through the condenser and radiator anyway, but at idle/traffic you need the fans spinning. Routine fix; either replace the fan clutch, or determine if electric fan/sensor.wiring is bad and fix.


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## netxtown (Jun 24, 2016)

Just a note from my lessons learned...

It's Texas. It's hot, and A/C is a must. Over the years, I really didn't notice it until I was heading home from work with the A/C on high and I was still sweatin...but the air blowing out was really cold!?! This went on for a few more days until I banged my head on something - and realized YES! the air was cold...but the air blowing out of the vents lacked volume.

A bit of research pointed me in the right direction. The cabin filter was clogged with about 120,000 miles of dust and dirt (and I was able to find that stinky tennis shoe smell!) Replacing the filters is a bit of a pia as they are located behind the glove box. Also, not sure why, but the replacement listing for my truck (2005 v6) was incorrect at the parts store. I had to remove the filters and take to the store to get matched up correctly. Turns out they were 2006 filters.

In any case - replaced the filters, and oh what a difference!


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