jsmoke32

I recently changed my Cabin filter, Air filter and recharged my AC at the same time.

Now my car is surging in while in Drive and is especially noticeable when I am stopped with my foot on the brake. The AC does not seem to be blowing as cold as it did before. When I turn the AC off the car seems to be fine.

I have tried to go through the many threads on this site but I still cannot seem to locate the problem. Has anyone had this same problem before?

jsmoke32

Probably should mention that my car is a 1993 LS400

dicer

So was your ac converted to 134?

jsmoke32

I am not sure as I have only owned the car two years. I did use 134A.

i dont like the sound of that question 😀

djamps

1993 was apparently the last year to come with R12:

http://www.techchoiceparts.com/refri...pacities/lexus

If you mixed the two, the compressor (and maybe more) is probably done for. The oils used are not compatible.

jsmoke32

Well thank you for all the help. looks like I will have a nice bill coming up. Previously I thought that 1992 was he last year. This one is on me, I should have posted before I did it!

jsmoke32

Wait...According to the list on your link, 1993 did come with 134A for the LS400 unless my eyes are playing tricks on me.

If that is the case, I still do not know why I have the surging problem. It doesn't surge with AC off or when the car is in Park or Neutral. The Air Cabin filter light is also still on even though I replaced it and disconnected the battery to reset it.

oldskewel

iTrader: (1)

The link djamps gives does show 1993 as being R-134a. That also fits with my understanding, and Lexus TSB AC001-98.

Your car probably has a sticker also in the engine bay saying you've got R-134a. So the type of refrigerant is not your problem. But maybe you overcharged it? From your description, it definitely sounds like it is the AC that is causing the problem.

oldskewel

iTrader: (1)

R12 to R134a AC Retrofit form Lexus .pdf
Here's the retrofit Lexus information, confirming that LS400 only had R-12 in 1990-1992.
Again, there should be a sticker to remove all doubt.

jsmoke32

It took me a little while to find it, but there is a small sticker on one of the electric fan shrouds that says 134A so that eliminates any conversion issue.

I filled it up with only 2 cans of collant and the pressure read between 32-35 which should have been within the acceptable level. Any other thoughts on what could be producing the higher idle level when AC is on? I did not have this problem before I filled the coolant or replacing the cabin filter and air filter.

oldskewel

iTrader: (1)

How empty was it before adding two cans? Two cans sounds like a lot. Measuring pressure (both low and high) can give an idea about how much refrigerant is in there, but even that is not conclusive. To really know, the pro's will evacuate the system, weigh it, and put it back in.

Was your system empty before adding two cans? Did you test it after adding one can? How much was in each can? Pure R-134a in each can?

Also, a clarifying question - our postings crossed above - I posted after you did, but before I read what you wrote ... Does the surging go away when the AC is ON, but the car is in Park or Neutral? If yes, then I'm less sure it's an AC problem.

djamps

My bad guys/gals, indeed, 93 and up apparently use r134a

jsmoke32

Looking back, I think I had one full can and one half can left. After adding the first can I did check the pressure. It had went up around 5 pounds if I remember correctly but still a little below the normal level per the instructions. So I added the other half can thinking I should be ok. Although I will admit my judgement isn't always correct.

Yes it was pure 134A in each can.

To clarify, when the AC is off the car does not surge at all. It only surges when the AC is on AND the car is in drive. It does not surge when AC is on and the car is in Park or Neutral, at least I do not see the RPM gauge moving during this time.

I have not worked much with AC units and do not believe I overfilled, but in case I did could this be a factor in the surging issue?

Thanks again everyone for all your help, really appreciate your time!

oldskewel

iTrader: (1)

I can't figure out anything else at this point. But one thing I would have done differently is to actually test the AC after putting one can in. The pressure tests are not as meaningful as you might think. If after one can the AC blew ice cold, I would have stopped there, regardless of pressure readings.

The fact that with AC ON and the car in Park, the problem goes away ...

Good luck.

jsmoke32

I did notice the RPM goes up slightly while still in neutral with AC on but only 150-200 higher. I am going to revisit cabin filter and make sure it is installed correctly. Any other suggestions are welcomed!