Yes, some of us still have use for AC this time of year in Florida lol.

In the process of changing heater core last month, i figured I would change out change evap and expansion valve as well (internet aftermarkets).

Afterwards I went to a place who said they recharged my a.c. and vacuumed it down when doing my starter, as a freebie. It was winter so I couldn't tell but I should have checked if the clutch engaged.

Well once i got to warmer weather, i noticed it wasn't working at all. Clutch not engaging. So I had to pay a shop $80 for a recharge and vacuum, because they said it was empty. All was working well for about 4 days, then it stopped getting cool. Compressor clutch engaging though. Both shops said no leaks detected

Instead of paying someone else again, i grabbed two medium sizes cans, and one small 3 ounce can with oil and a good quality gauge. One of the cans had stop leak (I know I've been roasted in the past for stop leak, but this was just included with the gas, not a whole can of stop leak). Recharged up fine. That was 3 weeks ago and it still seems to be cooling perfectly.

Only issue is it seems like I have to turn it down to 68/69 to blow cold enough thru the front vents. The rear vents seem fine. I don't know if maybe I did something by taping up the vent behind the ash tray leading to the rear because it was a gap between the connections. But it seems like once I idle, the vents get super cold at 65/66. And for the most part it gets cold, but seems to not get as cold on highway until after few miles and then closing the rear vent helps a bit.

Or may it be the automatic temp control adjusting things?

In some instances low refrigerant will cause output temps to be cooler at idle. You probably have leaks, and are experiencing one of the earlier stages of a low charge. Don't trust a quick "no leaks detected" diagnosis. They can be a real pain to find. Their diagnosis was probably more of a "we didn't hear anything hissing" or "it held vacuum for 2 minutes" when we added refrigerant kind of deal.

Might be your compressor is weak already, that's why you get hot air during idling, and cold one when driving.

Dxta wrote: ↑

Sun Mar 08, 2020 8:58 pm

Might be your compressor is weak already, that's why you get hot air during idling, and cold one when driving.

Well the compressor is fairly new, and so far it still runs good. However based on the replies about low Freon, I’m kind of wondering about the o-rings for the evaporator and expansion valve, considering the ones that came with it didn’t seem to fit well and had to reuse the old ones.

So far I’ve already had to do 3 top ups, the mechanic the first time, myself the 2nd time and the mechanic again the 3rd time. and now it seems like it’s running low again. Very annoyed.

Only reason I removed the evaporator was because of the heater core replacement earlier this year. Fortunately the evaporator is pretty easy to drop down and look at again.

Actually edit: the new aftermarket evaporator and expansion valve didn't have o rings included. I tried to use green prepackaged o rings, but they didn't fit. Once I installed it, i found a farm store that carries black neoprene o rings. I may end up having to re-do it as prior to this, the a/c worked perfect.

If you're reusing the old O rings, wrapped them with AC thread tape. That should be fine. But if you don't want to tear into the dashboard where d evaporator is, then getting a new one would be better.

98_Q45 wrote: ↑

Wed Apr 08, 2020 6:30 pm

Actually edit: the new aftermarket evaporator and expansion valve didn't have o rings included. I tried to use green prepackaged o rings, but they didn't fit. Once I installed it, i found a farm store that carries black neoprene o rings. I may end up having to re-do it as prior to this, the a/c worked perfect.

You definitely have a leak. Black O-rings are not always compatible with R-134a. The best is HNBR. Also, bear in mind that for proper sealing, o-rings must be of the correct cross section in addition to diameter. As to your initial question on the temperature vs. compressor speed vs. forward motion (heat transfer at condenser) you really need to know the high and low side pressures to accurately assess what is going on with the system.

3Q Jay wrote: ↑

Thu Apr 09, 2020 5:13 am

98_Q45 wrote: ↑

Wed Apr 08, 2020 6:30 pm

Actually edit: the new aftermarket evaporator and expansion valve didn't have o rings included. I tried to use green prepackaged o rings, but they didn't fit. Once I installed it, i found a farm store that carries black neoprene o rings. I may end up having to re-do it as prior to this, the a/c worked perfect.

You definitely have a leak. Black O-rings are not always compatible with R-134a. The best is HNBR. Also, bear in mind that for proper sealing, o-rings must be of the correct cross section in addition to diameter. As to your initial question on the temperature vs. compressor speed vs. forward motion (heat transfer at condenser) you really need to know the high and low side pressures to accurately assess what is going on with the system.

Well, when I removed the evaporator and separated the expansion block from its connector, the original o rings are black. (if anyone knows what I mean, the expansion valve doesn’t connect directly to the high side hose, there’s another connector with o-rings).

But I also seen some green ones here and there too. Hard to tell what’s going on. The evaporator looked original: and I changed it with the heater core because it had leaves around the bottom, and figured I’d put a new one in while it was already out. But O-rings can be so tricky to get right.

I'm not suggesting that the factory ones were not black. I am saying that not all black o-rings are created equal. My suggestion is to use HNBR o-rings (note that there are chinese fake green ones out there too.

3Q Jay wrote: ↑

Fri Apr 10, 2020 7:01 am

I'm not suggesting that the factory ones were not black. I am saying that not all black o-rings are created equal. My suggestion is to use HNBR o-rings (note that there are chinese fake green ones out there too.

Well I just did the unthinkable: didn’t want to take anymore chances so went ahead and ordered the 4 o rings in the evaporator/expansion valve area from Infiniti. The two hoses that go into it are getting aftermarket.

That way I know I’ll get the BEST and correct sized ones which require evaporator out, but the L and H hoses that connect from the engine I’m sure are universal.

3Q Jay wrote: ↑

Fri Apr 10, 2020 7:01 am

I'm not suggesting that the factory ones were not black. I am saying that not all black o-rings are created equal. My suggestion is to use HNBR o-rings (note that there are chinese fake green ones out there too.

Update: yeah even the new OEM ones came in black. But I used a package of AC pro green ones for the hoses. Being I've done it already, the job didn't take too long this go around. Just didn't like having to spend a day doing it again. Those hoses leading into the dashboard are in an area so tight. I have to use 3 extensions on a 3/8" just to be able to get enough room from halfway across the engine.

And yeah my evaporator was a Chinese knock off as well, didn't notice much difference in quality or performance from the OEM one, except the in and out hoses were far too close to the fins. so when I first did the job, I wasted hours trying to bend it back and forth in shape so I could slide the air filters in right and get it to line up with the way the hoses in the engine connect. The hoses go in very precisely, drove me crazy.

Going in tomorrow to recharge. I hope I'm Scot free after this. And off topic, I finally finally finally got all my a/c controller lights to light up. Bought a set from Amazon, they fit just right. After ordering 2 defective units from EBay, I just grabbed the one I got at pick n pull in Tucson Arizona couple years ago, that was working fine until I decided to switch the bulbs over to my unit. Since then I've been dealing with 1 or 2 sections that wouldn't light up, or non at all. Just drove me mad. So finally....making progress again.

Problem solved: It was NOT fixed back in April. That was a waste of $79. Had to endure 3 months of summer before figuring it out finally: there was a blockage in the liquid line caused by the drier, spitting desiccant. Desiccant went to expansion valve. To make matters worse, I used a “proven” stop leak thinking something was leaking. In turn, this created a permanent seal in the liquid line Near the expansion valve, which completely blocked the flow of refrigerant to the evap, which equated to hardly no cooling. No amount of flushing or chemicals could remove this seal. It was like a cement. Fortunately it didn’t get past the expansion valve to the evap and compressor.

In the end, I replaced the line and the 2 valves, the drier, and condenser (even though I have suspicions on whether it was actually leaking).

I think the whole cause originally: could have either been the drier was saturated from being left open (couldn't get oil pressure switch on awhile back, which equated to discharge hose being left open for a couple of days), or the place I had it charged may have over-charged it...which can cause the dessicant bag to rip. Even the junkyard liquid line I picked up, had dessicant material inside. Fortunately there was no stop leak clog.

All this originally caused because needed to fix my heater core. Lesson learned: take no shortcuts with a/c work and if a shop does it, verify how much is going in. One guy put in nearly 3-12 ounce cans. This involved about 5 trips to the mechanic before finally getting it right, and on the last time I brought exactly 25 ounces of r134 to ENSURE it was not overfilled. Now it’s putting out like 32 degrees in 90 degree heat in front and rear vents (even though rear vent “still” feels a bit colder, but only during the daytime: which I attribute to the windshield heat making it feel slightly less cold. Had that same feeling in a Pathfinder I rented last month.

I’m ready to just enjoy my q45 AGAIN and take a break from anymore major DIY projects lol. Especially HVAC which is never fun. But in the end, it was my DIY that ultimately fixed the issue. The mechanics in my area don’t want to be bothered with 90s foreign cars much.

Research and a methodical approach pay dividends!
Glad to hear you have taken the appropriate steps and not short cuts to resolve this issue

3Q Jay wrote: ↑

Sun Jul 19, 2020 7:25 am

Research and a methodical approach pay dividends!
Glad to hear you have taken the appropriate steps and not short cuts to resolve this issue

Lol yeah at this point I pretty much have learned to become an auto a/c technician. All I need is the certification lol.

Next to brakes and body work, auto a/c probably the biggest ripoff enterprises for a car. Rarely done properly, always over priced. My favorite mechanic owner in town got annoyed that I brought my own r134. I'm like yes lol. I don't want just enough for it to get cold, and I don't want overfilled.

Now it's blowing colder than I've ever had it. Almost TOO cold lol. At 74 is usually sufficient at night. 68 for 95 degree days. 65 mainly for first 5 minutes starting up.

Only downside is running the compressor makes the exhaust smoke like a chimney (does it regardless, but the compressor draw really adds to it), and have to keep an eye on the temp gauge in idle and stop and go. 1 of the fans seems to not keep up. Sometimes the fans will run upwards of 5 minutes after shut off.