No cooling fans issue

[Vincentjr]

So I’m having an issue with my coolant fans. I have heat and working ac system but no fans ever. I have hunted down other forums on this site and done many tests the low speed is working over as per jumping the AC red switch plugs. The two pin blue sensor on the thermostat housing when I pull that I get high fans. I have driven the car for two hours straight at times and I never have any fans including while running the AC I leave my HVAC in defrost with the heat on all the time we’re not using the AC. Not sure if my in operable blower motor/regulator issue which I have made a separate thread for ties into this in anyway but as I said in that thread I am at a total loss for this issue as well on my journey to save Satan‘s wagon green on tan any help or direction or other tests that I can do is greatly appreciated.

 

[gsxr]

Your tests confirm the fans, fuses, and relays are working.

Remember the low fans trigger based on refrigerant pressure only. The AC has to be running AND it has to be warm enough, with good refrigerant charge, to get pressure above 16 bar to turn the fans on low speed. If you can confirm with AC manifold gauges that the high side pressure is well above 16 bar and the fans are not running, you may have a defective red switch.

The fans only run on high speed when coolant temp exceeds 107°C. You should never see the engine get this hot in the first places, which is probably why the fans are not running on high speed.

 

[Vincentjr]

Your tests confirm the fans, fuses, and relays are working.

Remember the low fans trigger based on refrigerant pressure only. The AC has to be running AND it has to be warm enough, with good refrigerant charge, to get pressure above 16 bar to turn the fans on low speed. If you can confirm with AC manifold gauges that the high side pressure is well above 16 bar and the fans are not running, you may have a defective red switch.

The fans only run on high speed when coolant temp exceeds 107°C. You should never see the engine get this hot in the first places, which is probably why the fans are not running on high speed.

The AC was in operable before I put it on the AC machine sucked out the system tested it and then fill it up with the correct amount I’m gonna see if I can get my temp gauge to be way at the top of the 80 again so I can get a picture for here with no fans running I’m gonna try to borrow a thermal gun and hopefully it’ll put my mind at ease a little bit but one of the days I drove around for a couple hours it was like 90° out so that’s where I got a little confused

 

[Jlaa]

Your tests confirm the fans, fuses, and relays are working.

Remember the low fans trigger based on refrigerant pressure only. …. The fans only run on high speed when coolant temp exceeds 107°C. You should never see the engine get this hot in the first places, which is probably why the fans are not running on high speed.

The AC was in operable before I put it on the AC machine sucked out the system tested it and then fill it up with the correct amount

It sounds like you recently replaced the refrigerant? I wonder if you have the correct amount in there. What pressures are you seeing?

 

[gsxr]

I’m gonna see if I can get my temp gauge to be way at the top of the 80 again so I can get a picture for here with no fans running I’m gonna try to borrow a thermal gun and hopefully it’ll put my mind at ease a little bit but one of the days I drove around for a couple hours it was like 90° out so that’s where I got a little confused

It sounds like you are trying to create a problem where none exists. The unmarked line above 80C is 100C.

For the fans to turn on high, it would need to be almost to the 120C mark.

You've already verified the fans run on high when you pull the 2-pin connector off the sensor, that's all you need to do. What are you worried about? I'm confused.

 

[Jlaa]

It sounds like you are trying to create a problem where none exists. The unmarked line above 80C is 100C.

For the fans to turn on high, it would need to be almost to the 120C mark.

You've already verified the fans run on high when you pull the 2-pin connector off the sensor, that's all you need to do. What are you worried about? I'm confused.

I think he is saying his electric cooling fans never turn on - neither low nor high speed? I feel like the Cooling Fan TPS Report needs the “Executive Summary” rewrittten? . Just Kiddin‘ man. GenX folks are all about TPS Reports….

 

[gsxr]

I have hunted down other forums on this site and done many tests the low speed is working over as per jumping the AC red switch plugs. The two pin blue sensor on the thermostat housing when I pull that I get high fans. I have driven the car for two hours straight at times and I never have any fans...

I read the above as the high fans are working when tested... but the post wasn't clear. I'm pretty certain there's an Only Fans joke in here somewhere waiting to be exposed.

 

[Vincentjr]

I think he is saying his electric cooling fans never turn on - neither low nor high speed? I feel like the Cooling Fan TPS Report needs the “Executive Summary” rewrittten? . Just Kiddin‘ man. GenX folks are all about TPS Reports….

I had to ask my coworker know what TPS reports man and I got a good giggle out of it

 

[Vincentjr]

It sounds like you are trying to create a problem where none exists. The unmarked line above 80C is 100C.

For the fans to turn on high, it would need to be almost to the 120C mark.

You've already verified the fans run on high when you pull the 2-pin connector off the sensor, that's all you need to do. What are you worried about? I'm confused.

I’m just trying to be thorough with the old car. The low speed fans should run with the AC and I haven’t seen them do that and my worry is during the summer if I go on a longer drive I don’t want to overheat and get left stranded Mercedes has been very good to me since I’ve switched from Volkswagen

 

[gsxr]

I’m just trying to be thorough with the old car. The low speed fans should run with the AC and I haven’t seen them do that ...

This is not correct. ^^^ Read what I wrote previously. The fans run based on refrigerant pressure. THE FANS DO NOT RUN AT ALL TIMES WHEN AC IS ON. There is a difference.

...and my worry is during the summer if I go on a longer drive I don’t want to overheat and get left stranded Mercedes has been very good to me since I’ve switched from Volkswagen

To make you feel better, the low speed fans have almost nothing to do with engine cooling. They are meant to improve AC performance when stopped or in low-speed traffic, where the engine RPM is low and the mechanical fan isn't moving much air. The electric fans keep air moving over the AC condenser.

The primary engine cooling is from the mechanical fan with viscous clutch. If that is working properly, and the rest of the cooling system is in good shape (have you pressure tested the system & cap?), and you haven't seen engine temps above 100C (the unmarked line), it's probably fine. Look for a date on the radiator though, if original from the early 90's, it's on borrowed time.

 

[Vincentjr]

This is not correct. ^^^ Read what I wrote previously. The fans run based on refrigerant pressure. THE FANS DO NOT RUN AT ALL TIMES WHEN AC IS ON. There is a difference.



To make you feel better, the low speed fans have almost nothing to do with engine cooling. They are meant to improve AC performance when stopped or in low-speed traffic, where the engine RPM is low and the mechanical fan isn't moving much air. The electric fans keep air moving over the AC condenser.

The primary engine cooling is from the mechanical fan with viscous clutch. If that is working properly, and the rest of the cooling system is in good shape (have you pressure tested the system & cap?), and you haven't seen engine temps above 100C (the unmarked line), it's probably fine. Look for a date on the radiator though, if original from the early 90's, it's on borrowed time.

I have seen it get to the unmarked line like right up underneath it and a couple revs brings it back down normally

 

[JC220]

I had to ask my coworker know what TPS reports man and I got a good giggle out of it

Did have to Google that one too!

 

[gsxr]

I have seen it get to the unmarked line like right up underneath it and a couple revs brings it back down normally

It's not even hitting 100C. Many owners would love to see that. Completely normal... nothing to see here, move along...

 

[Vincentjr]

It's not even hitting 100C. Many owners would love to see that. Completely normal... nothing to see here, move along...

View attachment 147662

I appreciate you putting me at ease time to head back to the blower issue haha

 

[luckymike]

I hope you’ll either chime in on one of the good blower threads we have here or start your own. In the meantime, you might want to try the shortcut that I found in one of the threads: run 12 V to the rear side of the 30 amp fuse and see if that gives you power. If it does, I think That means your ignition switch is bad. I can’t confirm that until I replace mine pretty soon. But at least I have a fan now.

 

[Vincentjr]

I hope you’ll either chime in on one of the good blower threads we have here or start your own. In the meantime, you might want to try the shortcut that I found in one of the threads: run 12 V to the rear side of the 30 amp fuse and see if that gives you power. If it does, I think That means your ignition switch is bad. I can’t confirm that until I replace mine pretty soon. But at least I have a fan now.

I has started my own hope to see you there

 

[Vincentjr]

I hope you’ll either chime in on one of the good blower threads we have here or start your own. In the meantime, you might want to try the shortcut that I found in one of the threads: run 12 V to the rear side of the 30 amp fuse and see if that gives you power. If it does, I think That means your ignition switch is bad. I can’t confirm that until I replace mine pretty soon. But at least I have a fan now.

So I hooked power up to each side of that strip fuse this morning I did not get any fans but when I hit the side facing the hood I did hear it clicking around in the blower motor area

 

[gsxr]

So I hooked power up to each side of that strip fuse this morning I did not get any fans but when I hit the side facing the hood I did hear it clicking around in the blower motor area

OK now I'm confused again are you looking for the twin cooling fans to fire up or are you wanting the HVAC blower motor to run?

 

[Vincentjr]

OK now I'm confused again are you looking for the twin cooling fans to fire up or are you wanting the HVAC blower motor to run?

Both but now we’re on the blower issue cause you put to rest my cooling fears

 

[nocfn]

what is Only Fans..