A/C Suddenly Stopped While Driving- Fan speed?

[xDiesel03]

I was driving down the road the other day and the AC all of a sudden stopped working and the air got hot. I check power to the compressor, checked the freon levels, and checked to see if the fan is cycling on. The line is cold when the compressor is on but the air still blows hot. Using the VCM Scanner at idle the fan is at ~19rpm and with defrost or AC engaged it goes up to 30-40rpm. Seems really low for fan speed.

[Ackerdiesel]

The compressor is forsure engaging? Blower fan or engine cooling fan


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[4x4dually]

Ya, which fan? I have trouble with blower fan since the turds that designed it put the little connector down where the passengers feet keep kicking it and breaking wires. This wouldn't affect the temp of the air though, I just loose 3rd gear sometimes.

[BigPapa]

Sounds like a blend door issue if the line is cold.

[CorneliusRox]

Originally Posted by BigPapa

Sounds like a blend door issue if the line is cold.

Either this, or your low pressure line was just cold from it working a few minutes prior.

I would make sure the compressor is kicking on. If it isn't, your levels might be low (you've got a leak). You said you checked them, so if they're not low, I would assume it's your pressure switch. Sometimes they're mounted on the dryer, sometimes on the compressor itself.

If it's neither of those, it's likely your orifice tube.

[jesnic7]

Depending on which truck is the culprit, it could be the ceramic resister has toasted. It is in the fan cowl under the passenger dash. It controls blower fan speed. Most of the time, when the resister burns, the fan motor is toast as well.

[BigPapa]

Originally Posted by xDiesel03

The line is cold when the compressor is on but the air still blows hot.

From this line of his initial post I take it the compressor is still cycling and the blower motor is still blowing.

[CorneliusRox]

Originally Posted by BigPapa

From this line of his initial post I take it the compressor is still cycling and the blower motor is still blowing.

Yeah, I just wanted to cover the bases. I agree though with the blend door.

[xDiesel03]

Compressor is still cycling and blower motor is still blowing. The reference to the line was a few days after it quit working when I was checking the compressor. I took part of the dash off and checked the blend door - I can hear it moving when I switch from hot to cold. I need to find/check the pressure switch now, and if that's not it, I'm also leaning towards a clogged orifice tube.

[BigPapa]

Are you hearing the door moving or the actuator moving? The blend door issue is the part that connects the door to the actuator breaks. The actuator still turns but it's not connected to the door.

[diesel_importer]

Fan clutches are junk on these trucks. What are the Low/High side readings? That will tell you if the orifice tube is plugged up.



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[Red Sleeper]

^^ This. The actuator will still make noise but the door won't move at all due to the coupler stripping out.

A clogged orifice would create a decent amount of head pressure wouldn't it? Visible when using gauges.

[SixOhh]

I have done a lot of dodge A/C repair ( seems dodge A/C systems aren't as reliable as fords IMO) and ive seen every single component go out. my 3rd gen has probably had 4 complete new ac systems piece by piece

So if your fan clutch went out while at freeway speeds, lets say 50 mph or over you shouldn't notice it until you stop for a light or traffic. With the vehicle off, if your blower motor responds to each fan speed on the HVAC controls its not the resistor next to the blower motor.

A temp gun and gauges will be your friend here. BUT another thing you can do really quick is drop the 3 screws holding the blower motor in and take a look / feel at the evap coils in the air box.

Down here in texas the humidity is constantly high,

I was stuck on a job in midland and mine kept freezing up after an hour of driving. freon looked fine but i replaced the liquid line anyways.... same ****.... I finally dropped the blower motor and looked at the coils and BAM.... Algae was covering more than half of the surface area. I ended up covering my carpet with trash bags and soaking it down with foam cleaner and rinsing it with a water hose. lord knows how long it was partially clogged because its been exponentially better since then.

And if your in there you can look directly at one of the blend doors. looking up that blend door is re-circulation / max a/c or outside air. If you live in the south or anywhere with high humidity i recommend ALWAYS running MAX A/C.
that blend door actuator on my 07 broke in probably 09. i cut a stick to length and wedged it on there so that it would only recirculate less humid air from inside the cab and i never looked back!

(sorry for the novel, coffee just kicked in!)

[SixOhh]

Originally Posted by diesel_importer

Fan clutches are junk on these trucks. What are the Low/High side readings?



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AND EXPENSIVE!

[diesel_importer]

I've been using Hayden clutches from Rock Auto. So far, they've been ok.


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[SixOhh]

Good to know

[xDiesel03]

It's getting cooler now so AC isn't as big of a deal, but I plan to wait until it gets colder and try to switch temps from warm to cold and see I I can confirm the blend door. If not, I'll pull the dash to check, and go to the orifice tube if that doesn't work.

[CorneliusRox]

Orifice tube is much easier to do btw.