AC not cooling enough

[saneesh8]

My AC is not cooling enough. It cools, but just mild cold air. It was blowing hot air and i can of freon made it blow the mild cold air. The meter came with the freon can was showing almost at the end of the green side.

Checked so far
1) The electric fan is working fine with two settings (slow and high speed).
2) The dual temperature switch on the radiator is new.

The recirculate button helps a little, but not much.

What is the ideal PSI needed at the low port? I have a feeling that it needs more and the *.* meter came with the can is not good. Also i am planning to buy an AC manifold gauge like this -> http://www.ebay.com/itm/AC-Manifold-...4cfc2b&vxp=mtr. To test it, the high side should have 10x the low side?

Also what all are the common areas which can leak freon? My other car, never had to fill it. This one, was working fine last year and this year it is gone.

Thanks..

[tractorcrusher]

I was about to post the same thing... then I realized you're just a few miles away from where I am.

I was thinking about just doing a R134 recharge and see if that helps at all.

Freaking Texas...

[Blacklane]

After I replaced my compressor, thermal expansion valve, receiver/dryer, and added 32 oz of R134a, my system charged to 50/225 inches HG at 1500 rpm and 70F degrees ambient. Not quite the numbers I expected. I wonder if I have some air in the system. I vacuumed the system for 2 hours; I would think that would be enough.

[saneesh8]

Checked again. Seems the aux fan is not running only at slow speed. Bad temperature switch (dual switch) ? Seems both dual temperature switch and pressure switch controls it. Either temperature switch bad or not enough pressure?

http://www.unofficialbmw.com/images/auxfanz3.jpg.

Also noted that while car is idling it is bad and while running, it is a lot better.

[saneesh8]

Confirmed. My fan does not turn on high speed (Aux fan). This might be the issue with not getting cold when idle. Need to find it.

[Blacklane]

The front electric aux fan should turn on "normal" (low) speed when the A/C is turned on and/or when the coolant temperature reaches the low-temp setting of the temperature switch on the side of the radiator (usually 80 degrees C). The fan turns on "High" speed when the temperature switch reaches the high-temp setting (usually 88 degrees C). There are two relays in the under-hood electrical box that control the fan speeds. Some people have discovered the temperature switch being mis-wired from the factory to be the opposite of this.

Concerning the "gurgling" sound from the AC: that's probably normal. It's the result of the system pressure equalizing across the Thermal Expansion Valve after the compressor shuts off. If the system is overfilled with R134a, it would not cool efficiently since the gas would not have enough room to expand.

[saneesh8]

I remember this was running at high speed last year when i used it (that's after i changed the double temperature switch from OEM to pelican parts one). This year i had to fill the freon and never had to use AC this much till yesterday. So it all points to bad double temperature switch? The fan is coming on as soon as turn on the AC switch in low speed. But never runs at high speed. If the relay goes bad, it will do the same right? I will check the relay. Thanks..Narrowed it down to relay or double temperature switch.

[Blacklane]

I had a similar problem that turned out to be the plug at the aux fan. The socket for one of the three wires was not making the connection and I had to clean it. I don't recall the exact colors, but brown is ground (per convention), black is one speed (high, I think) , blue is the other speed (low, I think).

For your problem, I would jumper the plug to the radiator temp sensor to see if you can activate the fan. If yes, it's the temp sensor. Next I would look at the relays. I believe the normal-speed relay is purple. You can borrow one of those from the power top motor in the trunk (assuming roadster). The high-speed relay is yellow, and there are already two of those in the box.

In my case, I had to go to the fan plug and found I had 12v there. Plus I could get the fan to run by applying 12v to it, so it had to be the plug. Again, you can simulate the hot condition and resultant call for high-speed fan by using a jumper at the temp sensor.

[saneesh8]

Thanks..will do it and update. If the connector have something loose, then when it switches to high speed, nothing would be running right? It is either high or low? Or the high needs power on both?

Also if running on low freon should not do it right? By looking at the diagram, it should not because the temperature switch can bypass it.

[328 Power 04]

I don't know if there was more done to the cars above, but after changing the dryer and expansion valve on my Z3, with a proper fill with an automatic machine (whatever they're called), the A/C blows very cold. Yes enough for Houston, TX. Replace any and all o-rings you will see when you swap parts of course.

[saneesh8]

The Dual Temperature switch, have 3 pins. Which one controls which? The middle one is ground and left is high and right is low? So just short 1-2 or 1-3 (middle to left or middle to right).

328 Power 04. Why did you change the dryer and expansion valve? It was stop cooling after some time?

[328 Power 04]

At one point while driving, the A/C started getting warmer and warmer, although the compressor was working. At first I thought it was the compressor breaking, however it was capable of making pressure. I put it on the manifold and the pressures would go up and cause a near negative on the low side. Eventually after replacing the compressor, it still did the same thing... so I went to the expansion valve. When I took it off, it had some sort of black "trash" of unknown origin in the orifice. So I replaced it, along with the dryer for good measure, since it IS a filter and the system was exposed to air for changing the compressor (twice, once at first, and then back to original one). It works really well now.

Also, be VERY aware that an overfilled A/C system will cause it to run inefficiently, and warm.

[saneesh8]

Thanks..

I think i narrowed it down. When i patched from center pin to left one, fan ran at high speed, confirming that fuse and high speed relay is good. Also when i did to the right one, it ran at low speed. Then removed the double temperature sensor which is only one year old. It seems melted around the pins area. Then i just took the old one which i replaced last year as preventive measure. Connected that one and then kept it on top of a candle. Fan started running slowly and then after few seconds, at high speed. Put this old one back (OEM). Could not test it on the car properly, but seems it should work

I bought the one which died from pelican parts and it dies within a year. Brand Facet. Seems not good.

[rf900rkw]

Yes, but.... The radiator temp switch has absolutely nothing to do with the A/C.

[saneesh8]

It was worse in stop and go traffic. So i found about this. Still needs more work : . How much is the normal PSI for the low port? I used the meter which comes with the can to fill it (almost towards the end of the green section).

[Zoupe6]

I am under the impression that PSI is not used to fill the system. The system is filled by weight. They must purge the system and refill with a set amount of refrigerant. If wrong, it will not work correctly. Mine is weak now and I will be having it redone a shop, not a can I buy in the store. Honestly, I have rarely had good luck with store bought recharging cans. Last time I had good luck refilling my own AC is when they still used the R12 and you had to puncture the top of the cans.

[BladeRunner919]

I am under the impression that PSI is not used to fill the system. The system is filled by weight.

Exactly - they suck the refrigerant out of the system, then should vacuum test it to check for leaks, then refill with the correct weight of gas.

[saneesh8]

I need to check the pressure first and then the other stuff. Some kind of leak should be there. Otherwise how can a sealed system will leak?

[Zoupe6]

Potentially! What generally happens is that people store their cars or do not use the AC all winter. The compressor needs oil to continue to work properly, as well as the various seals. As the car sits the refrigerant will leak around these un-oiled seals. When you fire it back up after 5 months of non-use the seals get re-oiled and usually become more effective at sealing, but it doesn't matter because the refrigerant has been lost. I run my AC once a month when I can remember during the winter to keep this from happening. Well, this time I had the AC belt off for quite a while so I couldn't run it and low and behold it is low.

Using your method you could just get a pressure reading, note it, and then check it again some time later. Any measured difference might indicate a leak. I have not seen a pressure requirement for these cars. The only place I see pressure oriented filling procedures is on the back of these auto store cans. Essentially, the can is putting in refrigerant until a safe level of pressure is induced to the system. How much refrigerant actually goes in before this pressure is reached? Who knows?

[328 Power 04]

The best way would be to look for signs of leakage, that might be easier said than done. Look for oily spots around joints... ex: where the pipes connect to the compressor, piping to dryer, piping to expansion valve, piping to condenser.

What I did in a car I know had a leak (an E36 I was using in Europe) I replaced all the O rings while the system was empty. Costs very little to get a box of hundreds of A/C O-rings and replace them all while the system is empty. Usually an O-ring leak will be very evident. It will look like a hardened O ring that isn't 'malleable' anymore. Then put a new dryer in, and have it vacuumed and filled.


I don't think this is possible to do at home properly unless you have a vacuum, A/C filling manifold, and a way to exactly measure the weight of the R134a going in. You can try to calculate a half a can (for example), but when you attach a can to the vacuumed system, it will drain in a few seconds. I've done it on some BMW's at home like this, with these tools, but the automatic machine at shops will be much better.

I realize you're in Texas and it's hot (and getting hotter), but this is one thing you'll want to do correctly. If you can find a shop that you make an agreement with to collect the R134a, let you work on the O-rings, dryer, and possibly expansion valve, then come back and fill it for you (for one price), then you'll probably fix it all.

That is if your evaporator isn't the problem; I don't know if that's common on Z3, it isn't on E36. Changing all the O-rings will eliminate ALL chances of leaks in a system with INTACT condenser, evaporator, etc. I can think of 8 O-ring locations off the top of my head.

[Tommm]

I am under the impression that PSI is not used to fill the system. The system is filled by weight. They must purge the system and refill with a set amount of refrigerant. If wrong, it will not work correctly. Mine is weak now and I will be having it redone a shop, not a can I buy in the store. Honestly, I have rarely had good luck with store bought recharging cans. Last time I had good luck refilling my own AC is when they still used the R12 and you had to puncture the top of the cans.

I had the same concerns as you a few weeks ago. Then I spoke with my cousin who is a retired GM engineer. Basically if the system is blowing anything then the system lost "Freon" and all it needs is a recharge.

I bought a couple of cans of R134 from big lots for $8 a can, and one of the fancy hoses that come with a gage and a trigger. It was on sale at O'Reillys, from 25 to 20 which was the same price as the other hose with a gage. I followed the directions on the can and hose and the 134 was on the very low end of the green. I shook and tilted the can and when the needle was on the high end of the green I disconnected. So far so good. Since there was still some gas in the can, and I was never happy with the AC in my Astra I hooked it up to the Astra. Yep, it was on the low end. The Astra got the rest of the gas, and works they way it should have. I complained when it was new and they said it was within spec. Yeah, there was gas in it - the minimum.

Bottom line, unless air got into the system, all one needs to do is recharge. I chose not to recharge with a can that had sealant. If my car lost half a can in almost 14 years.... probably the same for you. I would spend the $30 and DIY. If you buy a season or two out of it you are ahead. If it doesn't work you have the hose for the next car, and are not out that much $ anyway.

[saneesh8]

I am back

When i heated up the double temperature switch with candle, it was turning on the fan at low and high speed perfectly according to the temperature. Connected it back to the Radiator and make sure that the connector is properly seated. Drove on 95F for half hour. Fan is running only at low speed. Turn the car off and AC off, fan stops. Turn AC on (engine stopped), fan runs at slow speed, turning on by the other circuit, not the double temperature switch. This makes me believe that the double temperature switch is not working in both positions. Double checked the points at the connector and when i patch them, it runs the fan without any issue on both speeds.

Somewhere i read that the coolant flow in radiator can cause this? I mean wont trigger the sensor properly. Car never overheated and coolant is at proper level. Heater was working fine when i tested after the coolant change last time. The radiator seems to be hot and the coolant tank, i can see it bubbles at hot and pressure. Also thermostat is <6 months old. When i removed the sensor, coolant came out, means it have coolant there.

I bought an OEM sensor from dealership to try it out. Will be getting it shortly. Did someone ever got into this issue?

Forgot to add, when cruising on highway, AC runs beautifully.

[saneesh8]

No one?

[Zoupe6]

I had mine recharged professionally. Works beautifully! With regards to that switch. If the auxiliary fan comes on when you push the AC button then you should have enough air flow to cool down the condenser and get cold air. Personally, I do not have an auxiliary fan anymore although it is wired to the Spal fan. In hot weather the AC suffers a bit if sitting still for a while. Not much traffic around here! Once moving, it's ice cold.

I am not sure about these cars, but yes, air in the system can alter temp reading at the sensor. My Aprilia motorcycle is notorious for this if I do not burp the system correctly. Although, the sensor in my motorcycle is at the very top of the system (i.e. this is the place where air gets trapped). The BMW sensor, at least on my car, is located towards the top of the radiator on the side, but not at the very top. Have you changed your coolant lately and bled the system correctly?

[BladeRunner919]

I am back

When i heated up the double temperature switch with candle, it was turning on the fan at low and high speed perfectly according to the temperature. Connected it back to the Radiator and make sure that the connector is properly seated. Drove on 95F for half hour. Fan is running only at low speed. Turn the car off and AC off, fan stops. Turn AC on (engine stopped), fan runs at slow speed, turning on by the other circuit, not the double temperature switch. This makes me believe that the double temperature switch is not working in both positions. Double checked the points at the connector and when i patch them, it runs the fan without any issue on both speeds.

Somewhere i read that the coolant flow in radiator can cause this? I mean wont trigger the sensor properly. Car never overheated and coolant is at proper level. Heater was working fine when i tested after the coolant change last time. The radiator seems to be hot and the coolant tank, i can see it bubbles at hot and pressure. Also thermostat is <6 months old. When i removed the sensor, coolant came out, means it have coolant there.

I bought an OEM sensor from dealership to try it out. Will be getting it shortly. Did someone ever got into this issue?

Forgot to add, when cruising on highway, AC runs beautifully.

Well the fan obviously works correctly as far as the air con in concerned. Is your concern that it doesn't ever run at high speed? If so, have you actually run the car stationary for long enough for the engine to get hot enough to switch to high speed? If you're driving around, it's pretty unlikely you'll run hot enough to hit the high-speed temperature.