Does anyone know if I can recharge my own AC?

I have an E36 M3

If I can charge my own...does anyone know what kit and where I can buy the kit and approximately how much it costs?

Otherwise does anyone know how much I would pay to have it recharged at a repair shop?

I live in San Diego

Thanks Dave

Assuming you have the newer R134 (I think that's it from my memory) and not the older freon then yes you can do this yourself. Just head out to walmart or any auto parts store. They will have a kit to hook it up and a can of R134. Should be around 20 bucks. The hose only hooks up to one side of the a/c system due to the different connection sizes. It's really pretty simple. Give it a go.

I believe that all E36s have an R134 system, but there should be a decal under the hood that tells you if is is R134 or not.

If it is R134, then you can do it yourself, as suggested above. If it is not R134, then a professional would need to do it.

I got a kit at Walmart for about $25. Make sure you get the one with the pressure gauge, hoses, connectors, and can of R134.

You will need to get a chart that tells you the proper pressure for your system. The proper pressure will be dependent on the ambient (aka outside) temperature and air pressure (which you should be able to look up online @ weather.com or a similar site).

Also, if you are losing pressure regularly, then you probably have a leak. You can buy a can of R134 that has a special dye in it. If you then shine a blacklight on the engine (after the A/C has run for a while), you should be able to find the leak.

OK this is looking good...theres a walmart nearby and I have 134 fitting.

So whats up with the chart....where do I find the amount of pressure I need?

If you give me the last 7 digits of your VIN, I can try to see if I have the chart for your car and reproduce the chart for you.

That would be great

SEH03481 those are the last digits

AMEN to your sig M3D! Do you think your A/C system is poor? I had mine checked two years ago and the guy said it was charged fine. I have never been happy with it though, it seems pretty week. I heard this criticism before i bought the car so i always just "lived with it", but maybe I have problems!?

What fitting do you recharge from ? The one on the firewall or near the front of the engine bay ? I think mine is a little low. I see a bubble in the sight guage.

Here is the table for determining the "Nominal A/C System Low Pressure". Note that this table works for ALL BMWs:

<TABLE><TR><TD>Relative Humidity (%)</TD><TD>Outside Air Temp (Fahrenheit)</TD><TD>R-134a Low Pressure (psi)</TD></TR><TR><TD>20</TD><TD>70</TD><TD>9</TD></TR><TR><TD></TD><TD>80</TD><TD>24</TD></TR><TR><TD></TD><TD>90</TD><TD>40</TD></TR><TR><TD></TD><TD>100</TD><TD>50</TD></TR><TR><TD></TD><TD>110</TD><TD>58</TD></TR><TR><TD>30</TD><TD>70</TD><TD>10</TD></TR><TR><TD></TD><TD>80</TD><TD>28</TD></TR><TR><TD></TD><TD>90</TD><TD>42</TD></TR><TR><TD></TD><TD>100</TD><TD>54</TD></TR><TR><TD></TD><TD>110</TD><TD>62</TD></TR><TR><TD>40</TD><TD>70</TD><TD>12</TD></TR><TR><TD></TD><TD>80</TD><TD>32</TD></TR><TR><TD></TD><TD>90</TD><TD>45</TD></TR><TR><TD></TD><TD>100</TD><TD>57</TD></TR><TR><TD></TD><TD>110</TD><TD>67</TD></TR><TR><TD>50</TD><TD>70</TD><TD>14</TD></TR><TR><TD></TD><TD>80</TD><TD>36</TD></TR><TR><TD></TD><TD>90</TD><TD>54</TD></TR><TR><TD></TD><TD>100</TD><TD>67</TD></TR><TR><TD></TD><TD>110</TD><TD>76</TD></TR><TR><TD>60</TD><TD>70</TD><TD>18</TD></TR><TR><TD></TD><TD>80</TD><TD>39</TD></TR><TR><TD></TD><TD>90</TD><TD>57</TD></TR><TR><TD></TD><TD>100</TD><TD>72</TD></TR><TR><TD></TD><TD>110</TD><TD>80</TD></TR><TR><TD>70</TD><TD>70</TD><TD>19</TD></TR><TR><TD></TD><TD>80</TD><TD>42</TD></TR><TR><TD></TD><TD>90</TD><TD>61</TD></TR><TR><TD></TD><TD>100</TD><TD>75</TD></TR>
<TR><TD></TD><TD>110</TD><TD>87</TD></TR><TR><TD>80</TD><TD>70</TD><TD>21</TD></TR><TR><TD></TD><TD>80</TD><TD>47</TD></TR><TR><TD></TD><TD>90</TD><TD>67</TD></TR><TR><TD></TD><TD>100</TD><TD>80</TD></TR>
<TR><TD></TD><TD>110</TD><TD>89</TD></TR><TR><TD>90</TD><TD>70</TD><TD>33</TD></TR><TR><TD></TD><TD>80</TD><TD>54</TD></TR><TR><TD></TD><TD>90</TD><TD>69</TD></TR><TR><TD></TD><TD>100</TD><TD>84</TD></TR>
<TR><TD></TD><TD>110</TD><TD>94</TD></TR></TABLE>

Originally posted by jmargo
What fitting do you recharge from ? The one on the firewall or near the front of the engine bay ?

You always recharge from the low-pressure side, which I believe is next to the firewall. Trying to connect to the high-pressure side can be very dangerous.

The connectors that come with the kits that you get at Walmart or your local auto supply shop, should have only a low-side connector.

Hey I wanna thank everyone for the AC help especially GPAPA

I went to walmart and picked up the kit which was $25 with the gauge
My Ac had been working but when it got hot it just wasn't cool enough

Turn's out the AC had very little pressure.
The last time it was charged was 5 years ago....so it was definately overdue for maintenance
I believe even the maintenance guide says the AC is supposed to be charged every 4 years.

So it was about 60 today with humidity of 50% supposedly
I filled it up to 25PSI accounting for engine heat which has to count for something being I've been driving all day.

The A/C is now colder than hell.......which is good, because I'll be ready when the hot days come around.

A/C gas does eventually get lost even if you don't have a leak.......it's a permeable gas which will eventually leak out (if not very slowly) though here and there.

But I would suggest that everyone go out and buy this kit......I can't believe I almost was going to go to a place to have it charged......when you see how easy this is you won't even imagine paying someone to do this........
and now I have the kit with the guages, so I can keep tabs on things, and even help out a friend.


Thanks Alot

Dave:boink

So is the low pressure hookup on the fire wall ? Is that the blue one ?

I just paid to have my a/c system checked out, turns out i had a bad o-ring on one of my lines, they recharged it with dye, no leaks, then used some 134a with a leak stopper in it(for extra protection). total cost $140.00

The l,ow pressure one is on the driver side....it is the smaller diameter valve....attached to the larger diameter piping....at least it in on my 95M3

Glad to hear it worked out for you m3d...Something else to keep in mind of the a/c is charged fine, your microfilter may need chainging. When the microfilter gets clogged up it can prevent airflow hence appearing like you have an a/c problem.

I can't say for certain whether the low side is at the firewall or not, but I believe it is. I'm sure an HVAC guy will chime in at some point and clarify this. Either way, the kits you buy at walmart and the like will only fit on the proper side, so not much need to worry.

Edit: Old topic where I was involved in this same discussion (http://www.bimmerforums.com/forum/showthread.php?s=&threadid=35650&highlight=R134a)
Summed up:
Low side is larger diam/insulated connection and near the firewall. That is where you fill it up. you fill the low side so that it 'sucks' the R134 into the system.

My AC hasnt worked at all since I bought the car almost one year ago. Being the idiot that I am, I forgot to check the AC in my excitement when buying the car. I think my compressor still works. Should i just buy this kit and hope that all i need is a recharge? Or should i go out and get professional opinion? Where should I go and what should i expect in terms of cost? The summer is coming up and i dont want to be stuck without air condition AGAIN.

oh yeah, i have a 1992 325i.....does it come with freon or r134a? My car is at home right now so i cant check....

it should say on one of the stickers under your hood Stupenal. I hope you didn't try to run your a/c much if it wasn't working. If it isn't charged, you won't circulate freon/oil through system. We all know what running any system w/o oil will do!

I just tested my A/C pressure and it read high. It was 54 where it should have been around 40. What do I do about it ? Let some out ? Have it redone ?

Jason

stupenal: I think your car uses the older R12 freon. I have the same year 325is and it uses R12. I hate how its R12 because its pretty expensive and you can't recharge it yourself. Its illegal for sale and only certain service shops has R12 in stock. They charged me $250 for just the freon not including labor. It's a lot colder than R134 though!

Originally posted by jmargo
I just tested my A/C pressure and it read high. It was 54 where it should have been around 40. What do I do about it ? Let some out ? Have it redone ?

Jason

Your AC system pressure is highly dependent on temperature. If the temperature was on the high side or if you didn't have enough airflow through your evaporator, then that pressure isn't out of line. Was your auxiliary fan running? Also, did you run the engine at around 2000 rpm while measuring the pressure? As you rev up the engine above idle, the AC suction pressure will drop some.

That could explain it. I will test again. The fan was running though.
Thanks

Anyone have a guess as to how much it'll cost to convert the AC to r134a?

Too bad you are in ca. I got a 20lb can of r12 in the garage.

can anyone provide pics of the proper place the connect the hose?

HELP :(

Hi, I've been following this thread and it looks like the kit I bought won't fit the correct connector.

This is the kit from K-mart:
http://www2.hawaii.edu/~roberto/ac_recharge_kit.jpg

Here is a picture of the connectors by the firewall. I've numbered them 1 and 2 for reference:
http://www2.hawaii.edu/~roberto/ac_connectors.jpg

Note that number 1 in the picture above is connected to this little sight window, labeled number 3. This window is on a cylindrical device located just behind and below the passenger side headlight:
http://www2.hawaii.edu/~roberto/ac_view_window.jpg

Now...
The kit will only fit on connector 2. And, when I put it on 2, it says 90 psi!!!!! WTF?! Ambient temperature is about 80 F, and humidity is about 60%, so the chart says R-134 should be about 39 psi, not 90. (This is with the car running and A/C on full blast.) Ok, so maybe that's the wrong connector. But the kit simply won't fit on connector number 1. Should I get a kit that DOES fit to connector 1?

Also, am I supposed to be seeing anything in that little sight window (number 3)? Currently I see nothing there.

(A few notes here, in case they are of any help)
- Connector 1 is connected to the sight window (number 3).
- The pipe which attaches to connector 1 to window 3 does feel somewhat cold.
- The pipe which attaches to connector 2 is warm. It goes to a belt-driven device where all the other drive pulleys are (compressor??).

I guess the bottom line of my question is, am I supposed to connect to number 1? Also, what should I see in window 3?

Hmm never mind... I think I may have found the problem. :atom

Originally posted by DesmoBob
Hmm never mind... I think I may have found the problem. :atom

So you're just gonna leave us hangin'?

yeah????

MUAHAHA! IT'S A SECRET! :evil2

Just kidding. :D

Actually, my problem ended up having nothing to do with the topic of this thread (recharghing). See below if interested in my problem.

But to answer somebody's question, the correct orfice to recharge is number 2. However, I think this question was answered in a previous reply.
http://www2.hawaii.edu/~roberto/ac_connectors.jpg
According to the schematic in Bentley, it is the one which goes to the compressor (the thing I described earlier as the belt-driven thing), which is 2. Do NOT touch connector number 1.

OK, so about my a/c problem... warning--the rest of this reply is :offtopic

After some detective work, I realized my a/c problem occurred the day after I hosed down my engine compartment. So I checked the fuses. There are about 4 or 5 fuses associated with the a/c system. Fuse 39 had blown. I replaced it and it blew again. I checked the wiring diagram in Bentley and fuse 39 is connected to the compressor relay. The problem turned out to be a wire from the compressor which connects to a coupler. At the point where the wire enters the coupler, the insulation was slightly exposing the conductor, and it was causing a short to ground (against the compressor body). So I removed the wire from the coupler, shrink wrapped the exposed area, zip-tied the end of the shrink wrap (lest the engine heat expand the shrink wrap), reinserted into the copuler and recoupled the coupler. Replaced fuse. Cold a/c, problem solved. The problem (exposed conductor) seems to have existed for some time. Apparently it finally presented iself after the engine hosing when the force of the water pushed the wire to contact a grounding body.

Now about the 90 psi I found in the low pressure line, note that I have not yet tested this theory, but I believe that the temporary suspension of compressor functionality had caused a buildup of backpressure in the low pressure line. Now that it is functioning again, I will have to re-test the pressure there.

Originally posted by DesmoBob
...Now about the 90 psi I found in the low pressure line, note that I have not yet tested this theory, but I believe that the temporary suspension of compressor functionality had caused a buildup of backpressure in the low pressure line. Now that it is functioning again, I will have to re-test the pressure there.

Yeah, if your compressor wasn't actually turning, then the system pressure will equalize between the high pressure and low pressure sides. 90 psig sounds about right. When the compressor is actually turning, the discharge or high pressure side typically operates at 200-300 psig and the suction or low pressure side typically operates at 30-50 psig give or take.

In the future, you can see if the compressor is actually turning by looking at the center of the AC compressor clutch. The engine driven belt spins the outer pulley on the clutch all the time and when demanded by the AC system, electromagnets engage the pulley to the center part of the clutch which spins up the compressor.

R12 to R134 conversion will cost somewhere between 500-1000 at different shop , for different model. a R12 recharge should cost $150-$200 .
Alot non-running AC systems just have leaks somewhere in the system. don't let those 'shops' fool you with saying that the compressor is bad when the only thing you need is a recharge w/dye. :)

R12 to R134 conversion will cost somewhere between 500-1000 at different shop , for different model. a R12 recharge should cost $150-$200 .

I have a 92 325is and had it converted from R12 to R134 for $154. BMW was going to charge me about $900. Shop around.:D

A BMW shop would have changed the compressor to an R134a compressor and flushed the whole system. You may also need to change the expansion valve and you should change the drier out of principle.

If the compressor and expansion valve are R134a comptible, you still need to flush all the mineral oil out and drain the compressor (never flush a compressor with solvent). Refill with the proper PAG oil. Vacuum for 1 hour and recharge.

Hi,

I recharged my A/C today too. According to the chart, the pressure was already at about the right pressure before filling. But I decided to add a bit since it's never been charged since 1995. So Exactly how much I added, I'm not sure. But at least the can is lighter now. The strange thing is, the pressure still reads the same after recharge. Any ideas why? Does it need a lot of refrigerant to raise the pressure a few psi? My system is showing around 35 psi. The A/C compressor never turned after before, during or after the fill, so I'm pretty sure I didn't overpressurize it to trigger the high pressure switch. Should I keep adding until I start to see that it has some effect on the pressure? I guess I'll wait for another temperature/humidity combination to see what the pressure reads out at that time.