A/C hot, no condenser fans or compressor 99E300

1756 Views 26 Replies 4 Participants Last post by 55Benz, Aug 3, 2017

55Benz

Discussion Starter · May 20, 2017

Hi Everyone. Last week while driving A/c air suddenly got hot. I purchase refrigerant and followed the instructions on resetting after the ec illuminated.
I hastily reset before writing down the code. Compressor come on but has occasionally for periods of less than a minute. I've tried to quickly add refrigerant while it's on with no success. Also according to my gauge the pressure on the low side quickly climbs when I try to add 134. This could be due to reading a value after the compressor has stopped running. Maybe? The pressure on low side according to my gauge was around 50psi. I let some gas out of the valve to lower it. I reduced it to about 10 psi. tried again to add when comp. briefly came on but no luck. Compressor only seems to come on when the car has not been running for 2 or more hours and I could get it or the aux fans to come on at all today. Fans turn freely by hand with no noted roughness. Fuses are all good in the engine compartment. I've run the diagnostics and will list their values below. Also I've been driving the car hoping the original fault will reappear but it has not and the ec light has not returned. Sorry I posted extra values. Thanks in advance for any help. It's hot here in Wilmington NC!
1 - 82
2 -78
3 -87
4 -87
5 -134
6 -94
7 -03
8 -82
9 -27
10-2.3
11-1.5
12-4.3
20-3.2
21-32
22-00
23-32
24-11.6
40-164
41-85
42-08
43-136

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mrboca

· #2 · May 20, 2017 (Edited)

Hello

Obviously you took the readings with the engine off (from the battery reading). You need to take readings with the engine running and a/c working.

Coming to your real problem, your evaporator sensor is bad, and that is why you get warm air after a while. The evap core is freezing restricting coolness transfer to the airstream..

Do not play with the refrigerant. Fix the evap temperature sensor issue first, and then you can add refrigerant as needed.

And it is good that you posted the extra values. Otherwise how would we know what your battery voltage was and determine whether the car was running or not

#24 = 11.6V

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mrboca

· #4 · May 21, 2017

Check the fault codes from the hidden menu on your a/c control unit.

Follow the link to retrieve the codes, record post them here, and then reset the codes per instructions. You need to clear the codes related to refrigerant fill for the compressor to run, so you can put more refrigerant.

STAR TekInfo

When the system is stable, engine cooled down overnight and the coolant / refrigerant temperature is close to outside air temperature, the refrigerant pressures in psi on high / low side should be about the same as your outside temperature. If you have 80 degrees refrigerant temp (#8 in the list) the pressure should be about 80 psi or between 5 and 6 bars. You have low refrigerant level it seems.

Once you clear the codes the compressor should run for you to put some refrigerant (make sure you purge the air out of the manifold / charge hose prior to fill to prevent letting air into the system.

Your fans should start running when the high side pressure is about 15 bars (#7 in your list).

You do not need the compressor running to get the fault codes.

The evap sensor will not affect the compressor running up to a certain point. Your compressor should start running with a bad sensor but soon the evap core will freeze over and you will get warm air.

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mrboca

· #6 · May 21, 2017

Sure, you can press BOTH AUTO buttons for 15 to 20 seconds simultaneously and hold, the fans should come on at full speed.

If you have a scan tool that can access the 38 pin connector, and can access the a/c module, you can turn on the fan(s) at different speed stages.

Your compressor is not turning on because you have too little refrigerant. You can try the version coding for the controller to ignore the refrigerant pressure, so the compressor should turn on after you set the P2 to read 152 in the attached.

STAR TekInfo

By looking at your #43 (another benefit of providing the whole list

), the value is 136 which indicates that the controller check the refrigerant level and switches off the compressor if the refrigerant is low. This is really a redundant feature as your compressor has built-in mechanisms to protect itself from low refrigerant levels.

Follow the instructions to add 16 to 136 which makes it 152. So after this procedure, when you list your sensor values #43 should read 152.

Then you can charge the refrigerant once the compressor is running. If the compressor still does not want to run, let us know .

A good scanner should be able to tell you the status of the compressor running or not.

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mrboca

· #9 · May 21, 2017

1) replace your evap core temperature sensor.

https://www.amazon.com/s/ref=nb_sb_noss?url=search-alias=automotive&field-keywords=2108300772

You do not need to buy the OEM. Just buy the one that has good reviews and price.

2) You may have a sticking duovalve. You can address it after you get the evap temp sensor replaced.

3) Was the car and a/c running when you took the readings ?

4) Do not add more refrigerant until you address the evap temp sensor issue. One step at a time.

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mrboca

· #11 · May 22, 2017

Forget the a/c, and fix your charging circuits first.. While idling, you should see a minimum of 13.1-13.2V at #24 and you have 12V. Your car was running on the battery, not on the alternator. And I would not expect the things work properly, especially when you turn the a/c on with high current consumers like the blower and the electrical fan. Low voltage and charging problems can affect many modules of your car.

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mrboca

· #14 · May 22, 2017

The evap core temperature in your case should be around the same as #8 which is a bit more than 100 degrees F. It is the temp sensor that gives the false readings.

Check your serpentine belt , tensioner and the idler pulley. If your compressor is not able to turn with the clutch engaged, the belt will slip and generates heat on the pulley, and there is a thermal fuse inside the clutch mechanism which will open to cut the power to the clutch coil, and it will disengage the clutch. This will protect the belt from snapping off.

You should be able to turn the compressor off by pressing the EC button. When the red light comes up the compressor is turned off, and pressing the EC again will turn the red EC light off and the compressor should turn on.

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mrboca

· #17 · May 25, 2017

Is low side 100 psi with the engine running ? It would make almost 7 bars which is higher than the high side (5 bars) ? Are you sure the compressor is running ?

If the systems runs properly the low pressure side should be about 2 bars.

Follow the tests in the attached. Especially test condition 3 (with the temp setting set to HI.......rpm 1500. Does your low pressure gauge pulsate ????

STAR TekInfo

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mrboca

· #22 · May 25, 2017

#7 is the high side pressure which seems to be lower than your low side pressure

.

There is a hex nut in the hub, and when you run the a/c with EC not lit, the hub should turn. when you press the EC to turn the compressor off, the hub should stop spinning.

It is possible that your compressor is actually turning but set to kind of freewheeling (minimum piston compression), so the compressor is not compressing. If this is the case, maybe you have too much refrigerant, or the compressor control valve is bad or both.

Recently someone else had a similar warm air problem, he let some refrigerant out, and the system started cooling.

But the first thing is to make sure that compressor is turning when it is supposed to.

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mrboca

· #24 · May 25, 2017

If the hub is turning, the clutch is doing its job. It is just the swash plate in the compressor is in perpendicular position so the pistons are not compressing the refrigerant.

Check the attached link out for the Denso compressor. (it is in Russian, if you are using Chrome, right click on the page and press translate to english)

https://ukond.ru/schema/schema-compressora-7sb16c-denso/

You see the valve in the rectangle at the top ? That controls the compression ratio.

You also see how the clutch works. If the coil in the pulley is energized it will engage the hub which will turn the compressor shaft. If the swash plate is not at an angle, the 7 pistons will not move much. You may have a stuck
/ defective control valve

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mrboca

· #26 · May 26, 2017

The swash plate compressors are pretty hardy. Usually the control valve goes bad. You need to keep the static pressure at about 70 to 80 psi at the low side when the compressor is not running. If you can find a control valve suitable for your compressor at a JY it may be worth a shut before a major surgery. The new ones cost about 20 to 25 bucks but you need to know which one to buy.

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