Will cabin blower or regulator switch keep air conditioner compressor from engaging?

Changed regulator in June 2010--a year ago. Today, added refrigerant, but the clutch on compressor was not engaging the compressor, so compressor was not spinning.

Last year, I got a blower regulator switch on net from Autohauz for about $100 and installed it last June. I don't think the regulator is bad, but don't know how to test it.

Today, I turned on the A/C and nothing came out of the vents, Then I switched on the heat, and still nothing coming out of the vents. I don't know if a bad regulator, or bad blower would keep the air conditioner compressor from engaging.

So, some questions:

1. Will a bad cabin blower or regulator switch keep air conditioner compressor from engaging?

2. Would like to isolate the blower to see if it is working. How would I test the blower separately from the regulator to see if it is a blower problem?

Thanks

 

Hi Pancho,

As of today I'm experiencing a very similar problem here in NYC. The A/C was working perfectly two days ago when I last drove the car. Today I started it up this morning to drive to work and no air came out of the vents.

I noticed that I could still feel cold, "air conditioned" air just slightly trickling out of the vents while driving. When I got on the Manhattan's West Side Highway and hit 40 mph I could definitely feel air conditioned air coming out of the vents.

All signs point to the blower not working, but the compressor continuing to do its job. As we just hit the first day of summer I also need some expert advice about how to troubleshoot this and how I can get this fixed for the best price.

If there are no replies to both Pancho's and my similar issue I may start a new topic, but hopefully someone out there can help.

 

Trudawg's recent post has some good info from MarcusF but it's a different problem and I don't know exactly how to translate the info to the blower issue: https://mbworld.org/forums/clk-class...elp-im-az.html

I wasn't aware that diagnostic codes could be displayed on the climate control display, so that's very cool to know.

 

As mentioned here, apparently it could be as simple as the fuse:
https://mbworld.org/forums/clk55-amg...t-working.html

 

Pancho: I found your thread where you show the detailed photos of swapping out the regulator yourself. You're way beyond me with mechanical skill/experience

 

The same question was posted on another (much slower to load) forum. I think I responded there. Or somewhere. I loose track. At any rate, it sounds like your regulator is bad. Here's a link that will tell you how to fix it. It's about a 20 minute job.

 

Thank you Marcus! I had literally just found that after doing a google search for "blower" restricted to the "marcusfitzhugh.com" domain. I had a feeling there would be something

Question: is that fan next to the regulator the fan that actually pushes the air through the vents in the cabin, and you're suggesting that it's much more likely that the regulator is bad than the fan motor itself, with these symptoms?

 

"I think" it's the regulator. It could be the fan, it could be wiring, it could be a fuse, it could also be the mega dollar HVAC controller , but you can do some tests before spending any money. Use a volt meter and confirm power is coming from the plug that feeds the regulator. After you confirm there is power, it's either the regulator or the fan. You can then test the fan with a simple jumper. Just unplug the two wires that run from the regulator to the fan and apply current. I highly recommend that you do not leave the regulator plugged into the fan when you perform this test. If the fan moves with power, we know the fan works. Then you can plug the three prong input plug back into the regulator, and use the same volt meter to test whether power is coming from the regulator. If not, it's the regulator.

Pancho, I think this may have been the test you wanted too.

 

Ok, I almost purchased the regulator on friday from autohaus and now i'm glad I didn't.... I think. I borrowed a volt meter and tested if any power was going to the fan from the regulator, since that was the easiest test (let's keep in mind that this is the first time I've ever done anything to the car, or any car, beyond swapping out blown headlights).

With the leads attached, I got a range of 9V - 12.2V coming out of the regulator. There are seven fan speeds on the dash control and although I don't remember exactly, I believe it hovered around 9V until I increased the speed to the last 3 or 4 levels, and then it went to 10.8 and then 12.2 volts. It might have started at 3V, or maybe that's what it was at with the fan off. I would kind of expect each fan speed adjustment up to increase the voltage slightly, so is what I observed normal?

Then I reconnected the blower and noticed that the leads on the wires coming from the regulator are completely green, brittle and corroded. The positive lead sparked a bit with the fan speed on high, and while that happened I could feel the blower motor jerk forward just slightly - not even close to actually spinning, more like a jolt where it moved an 1/8th of an inch and then gave up. Unfortunately I don't have a garage or a 12V power supply or the right tools to apply a steady, reliable current to the blower, but I'm sure it got 12 volts long enough that it should have spun up if that's the max power it would ever get.

Finally the connector on the positive lead actually broke in half it's so brittle from apparent contact with moisture. The regulator itself and the metal around it seemed to have a lot of corrosion.

Based on what I saw am I looking at a working regulator and a blown blower motor, or are both bad? More important, is there a lot more moisture getting in there than normal causing these components to fry?

I noticed water dripping on the passenger floormat a few times after going through a carwash while leaving the air blowing, and I read about that happening to others somewhere on the forum.

Any thoughts?

 

Something tells me the problem described in this post is the culprit: https://mbworld.org/forums/clk-class...-footwell.html

 

Apparently my next door neighbor is one of the gurus on the circa 1996 Volvo 940 forums, and he happened to be changing his oil next to me in our lot. While I had nothing but the same tool bag I use to fix computers, he had the whole she-bang of tools, including the torx 20.

One of the first things we did was hook the blower directly up to his battery, and it spun up just fine! That seems to point back to the regulator as the culprit.

For extra credit, I decided to measure the control voltages coming from the three prong plug that goes into the regular for each of the 7 fan speeds (I assume these are coming from the magical HVAC controller), and then the voltage coming out of the regulator and going to the fan for those same 7 fan speeds - needless to say the positive lead on that connector tested at a healthy 12V:

fan speed / control voltage / voltage coming out of regulator:

1 / 1.28 / 8.88
2 / 1.34 / 8.88
3 / 1.74 / 8.88
4 / 2.21 / 8.88
5 / 2.77 / 8.88
6 / 3.36 / 8.88
7 / 5.10 / 12.01

I don't understand why the fan won't spin at all even with it set to HI in the console, but I also don't think the regulator is supposed to send the same voltage to the blower for speeds 1-6.

I also figured out where the little drain flap is referred to in this post, https://mbworld.org/forums/clk-class...-footwell.html, and sure it enough it was completely clogged with dirt, pine needles, and leaves.

 

Hey Marcus, Brasil, thanks for responding to my posting. I got immediatelly busy after I posted, and have only now read your responses. Seems that the building next to my office burned, as in caught on fire, and my building received severe water damage. Have been moving my office to new temporary locus, dealing with adjusters, cleaning crew, moving, finding new space, etc. Aint life grand?

Will do the testing to determine if my blower is out. Just replaced the regulator a year ago, so would be surprised if it's a regulator problem, but will test both the regulator and the blower, and do a clean out on the water drain. Won't get to it for about a week or two, and then will do a follow up. Just bought some A/C gauges and hoses, and friend and I are going to go in on an electric vacuum pump from Harbor freight $100. Needless to say, with the temp at 100+ around her, and the necessity of a suit and tie for my work, I am driving my old reliable Jeep ZJ, with good frosty A/C. Will stay in touch. Again, sorry I was not able to get back to this topic any sooner, and thanks again for your good info.

 

Bro all I can say is that you are the man!

I've been going crazee for days looking for instructions and pics on how to fix this darn thing. Thanks Marcus.