Convert AC from R12 to R134a - The Saga of Njordi

[Boerderij_Kabouter]

Next project on Skadi is to address the complete lack of any AC. I am going to convert to R134a, flush, and recharge the system while crossing my fingers that I do not have any leaks. When I press the valve on the lines I get some flow of refrigerant (very low, but something).

Here are the parts: conversionkit (88840-33020), 2 o-rings (90099-14044), 1 o-ring (90099-14045) and I have attached the Toyota service bulletin.

I was planning to have my shop do the flush and refill. Anyone have tips or things to be careful of?

134a retrofit service bulletin.pdf

[Boerderij_Kabouter]

Also getting crazy vibration when the AC is turned on sometimes.

Here is my relatively normal idle:

https://youtube.com/shorts/PXnkwxMjz...th2VwbXDXvNGFJ


And here is when the AC compressor is turned on:

https://youtube.com/shorts/xJEBUdnqY...8N4JkyKZfBQQbv

It does not always do this, but it shakes like this occasionally.

[Previologist]

Not sure how much a flush and oil replacement is, but I was quoted $280 for just an ac recharge on mine (with an empty system) and it cost me $40 to do it myself-4 cans of R134a, plus 300 deposit on rental equipment that was refunded upon return.

[Boerderij_Kabouter]

I had not thought of renting the equipment. Great suggestion!

[Boerderij_Kabouter]

Poking around through old threads and watching videos, it seems like the vibration is a symptom of a bad SADS... dun dun dun. Going to need to get this thing in the air and take a close look at the SADS.

[man_btc]

Just my 2¢ - if stationary with the van in Drive and no AC it doesn't sound like someone throwing a box of pots and pans down a flight of stairs (vs at idle but in Neutral), don't be so quick to assume it's the SAD couplers vs the compressor itself.

Also - FWIW After no AC for years, I got ambitious and had the local dealer do an AC retrofit prior to loading up with 6 people for a 2-hr summer drive to the airport. After returning a couple days later - no AC with further analysis indicating leaks "everywhere," so maybe plan on doing some leak testing with dye before just replacing seals related to the refrigerant conversion.

(Also - yeah, I know, I know - the dealer - I was on a short schedule (had just done the head gasket) & ignorant/scared of dealing with the AC stuff, alright? So I went to the "experts." Not that I was encouraged by the check-in guy's first question: "How do you pronounce 'Previa'?")

[Boerderij_Kabouter]

Where does the factory service manual describe removing the front bumper?! Can't find it anywhere!

[Previologist]

Don't know about the FSM but when I pulled the bumper off my 93 parts van I just went by the search and find method. IIRC you have to take the grill off, which is the trickiest part to do with breaking the clips.

[Boerderij_Kabouter]

Haha, yep, I found out about the clips the hard way. I broke one, and will now need to find. I think that I will have enough room to get at everything for the condenser and dryer through the grill area. I ran out of steam yesterday, so probably next weekend before I get this done.

[Previologist]

if you can't find one send me a picture. I should have an extra but may need a picture to ID it in my pile o parts.

[John Kaufmann]

Where does the factory service manual describe removing the front bumper?! ...

In 135 pages, the FSM does not cover either bumper.

[Boerderij_Kabouter]

Install is done, pressure testing now. Pray for me. Ha.

I put in the 134a conversion kit, new compressor, new condenser, new dryer, and new front evap valve. And all new orings. Install is pretty easy, but the front bumper definitely needs to come off.

PXL_20250709_142318559.jpg

PXL_20250709_133714437.jpg

The plastic bumper has 3 easily visible nuts on the underside that connect to the metal bumper frame. Then 5 nuts are hidden up inside the bumper that need to come out. 2 bolts hold bumper extension support arms toward the sides. And there are two super hidden bolts holding the very extreme right and left sides of the plastic bumper to the frame. These seem like they are easy to break, because one of mine is already broken. Then the plastic bumper just comes right off. Once on the inside, there are 8 bolts holding the metal bumper frame to the vehicle frame. Then everything is off and you can easily access the condenser and dryer. I hope that helps.

PXL_20250709_131634653.jpg

[Boerderij_Kabouter]

Ran the vacuum pump for two hours to dry everything out. Gauges have not budged off -30psi after being setup for the afternoon. I think I did it!

I will recharge it once I get the steering done, and the engine oiled and coolant added. Hoping to start up and get it running by this weekend.

[Boerderij_Kabouter]

The R-134a charge on a Previa with rear AC is very conveniently 1020g which works out to be exactly 3 cans of refrigerant. Charged it up this morning and am blowing ice cold air! Thrilled.