ac knock

raif281 · #1 10-11-2016, 04:56 AM

looked around a little bit on here but i didn't find anything yet. I have an 07 mazda b2300 standard with 109,xxx miles 4 cylinder engine not sure the size. But the ac is being funny, by that i mean on max ac is it always super cold no matter where i adjust the thermostat. On ac it is the same except hot no matter where it's positioned. Also there is a knocking sound whenever i turn it close to all the way to the left and all the way to the right. I flushed the heater core with nothing changing, i only did it because i did it on my jeep and said why not. thanks in advanced

raif281 · #2 10-12-2016, 03:32 AM

nobody?

Soledad · #3 10-12-2016, 06:01 AM

raif,

Unfortunately I'm not super familiar with the HVAC systems in these trucks but if I had to guess I would say that it seems as though the blend doors aren't working properly. Your truck isn't quite as old as mine but perhaps there's a vacuum line issue affecting the A/C selection and blend doors?

Also, as for the knock, I assume that sound is coming from the interior and not from the compressor under the hood?

Hopefully others more familiar with have some suggestions.

tomw0 · #4 10-12-2016, 06:32 AM

I bet a donut soledad has hit it on the first bam of the hammer. The blend door will move back and forth to adjust the temperature coming out of the HVAC system. Some have an electric motor that positions the door. Some use a cable.
The electric motor option has to 'know' where the blend door is before it can position it to hot or cold or somewhere in the middle. Old designs calibrated by whamming the door full open or full closed, let the motor exert all its force, and figured "we are HERE" based on the command sent to the motor. Moving to another position just them meant apply some juice and count the pulses of a wheely thing inside the motor. So many counts per so much motion of the control and it worked.
You are getting noises at the extremes, where the motor is trying to open more or close more, depending on design. I think it is broken. The hinge pins don't like being pushed all the way open or closed, and break after so many cycles. You can remove the motor and inspect the pin for damage. There are(may be) repair solutions on the web that do not require total removal of the dashboard. I suggest searching for "ford blend door repair" on the web.
tom

raif281 · #5 10-12-2016, 10:04 AM

Quote:

Originally Posted by Soledad

raif, Unfortunately I'm not super familiar with the HVAC systems in these trucks but if I had to guess I would say that it seems as though the blend doors aren't working properly. Your truck isn't quite as old as mine but perhaps there's a vacuum line issue affecting the A/C selection and blend doors? Also, as for the knock, I assume that sound is coming from the interior and not from the compressor under the hood? Hopefully others more familiar with have some suggestions.

me either as i just acquired it an my mother didn't have it long either. i believe the vacuum line is workin cuz it equalizes when i turn it off. thanks anyways man

Quote:

Originally Posted by tomw0

I bet a donut soledad has hit it on the first bam of the hammer. The blend door will move back and forth to adjust the temperature coming out of the HVAC system. Some have an electric motor that positions the door. Some use a cable. The electric motor option has to 'know' where the blend door is before it can position it to hot or cold or somewhere in the middle. Old designs calibrated by whamming the door full open or full closed, let the motor exert all its force, and figured "we are HERE" based on the command sent to the motor. Moving to another position just them meant apply some juice and count the pulses of a wheely thing inside the motor. So many counts per so much motion of the control and it worked. You are getting noises at the extremes, where the motor is trying to open more or close more, depending on design. I think it is broken. The hinge pins don't like being pushed all the way open or closed, and break after so many cycles. You can remove the motor and inspect the pin for damage. There are(may be) repair solutions on the web that do not require total removal of the dashboard. I suggest searching for "ford blend door repair" on the web. tom

thanks i'll have to reread that to understand it later lol. i tried getting access to the blend door yesterday on my own without researching anything and came to the conclusion it's a PITA to get to the screw closest to the engine an wasn't doable. thanks tom i'll do that soon.

cowboybilly9mile · #6 10-12-2016, 10:19 AM

Blend door problem; proof is how it is cold on ac max and uncontrollably hot in any other function/temp setting.

raif281 · #7 10-13-2016, 08:06 PM

guess ill try to change the blend door this weekend

Tyler46 · #8 10-15-2016, 03:39 AM

Quote:

Originally Posted by cowboybilly9mile

Blend door problem; proof is how it is cold on ac max and uncontrollably hot in any other function/temp setting.

This

Blend door actuator went bad. For sure.

$45 on eBay, problem solved. It's a bitch to get a socket in there but you can do it.

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Sorry for my post being chopped up. iOS 10 probz

tomw0 · #9 10-15-2016, 07:32 AM

All those part just to change the air temperature. I have a lever, cable, and arm moving the flap in mine. Works great. Knock on wood.
I realize electronics can be manufactured cheaply, but it may be assembly cost that is being cut as all you do is screw it in place in a sub-assembly line, and feed it to the main & snap the wiring harness. A wash? Dunno.
The white spline is the part that breaks on some, or the hinges for the flap.

HF and other places have very small ratchet wrenches that have an internal hex drive that you flip to change from tighten to loosen. They will fit into small spaces with limited access. They have a hex to 1/4" drive(or maybe it is plain hex drive) and a few sockets in the kit, along with a philips and flat screwdriver blade.
If you ever have to remove screws on top of a dashboard, where any tool would bump into the windshield, this setup might help.
tom

Tyler46 · #10 10-15-2016, 10:52 AM

On mine it was the little electric motor that was burnt out, and of course it had to be stuck open to the heater *sigh*

In the meantime I just ditched it and every time the flap pops open, I would just reach in the glove box and flop it back. Had to go bad on me when it was 100* out right? Lol

Good way to test Is take the device out, plug it back into the wiring harness, turn the key on and start toggling your center knob HVAC controls.

cowboybilly9mile · #11 10-15-2016, 12:46 PM

Quote:

Originally Posted by raif281

guess ill try to change the blend door this weekend

Suggestion before diving in.......if you look at the top of your currently installed actuator and with the vehicle in the run position, you can see a portion of the actuator (shown in second pic a few posts up) that will rotate CW and CCW when the temp control is adjusted. If it rotates, then the problem is probably not the actuator itself, it's.....the stinkin' section of the shaft on the blend door itself that engages with the actuator. It's a double D configuration.

***The good news for you is, the blend door itself problem seems to be most common on the 95-98 (or maybe 2000) models and quite infrequent after that.

raif281 · #12 10-16-2016, 07:36 PM

thanks for the input guys, ohh an for you tyler i have an iphone with ios 10 also. i find it easy enough to just copy an paste in notes then post it back onto the forum. same thing is happening on my jeep app. i hear ya bud south louisiana is bad too, thankfully ac works in max ac, even tho i freeze i can point the vents away from me an be ok.

tom i'll look into a set or see if my cousin who is a mechanic has something i can use, as it never hurts to have more tools.

billy i'll look into that this week if possible since i didn't get a change to this weekend. i was working on wiring up lights on my jeep and next weekend need to change the power steering line on my gf's truck that's leaking. and thankfully, i need all the luck i can take lol.