A/C Experts Assemble!

"JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t" (jawzx2)
07/05/2019 at 22:07 • Filed to: None

My Zetor Major 80 (a tractor) seems to be in need of a an A/C recharge, the vents blow very slightly cooler than ambient, which is less than ideal in mid-summer.... in any case, here’s the problem: I cannot find the damn low- pressure service port! I know its an r134a system, and that it takes 1.8lbs of coolant, I have found the high-pressure service port, but I cannot find the low- pressure port... I have followed the hoses as far as I can be tw een the compressor, condenser, expansion tube, and cab with no sign of a low-pressure service port. I have opened the blower cover on the roof of the cab and can see where the hoses connect to the ev aporator, but there’s no port there either...

Is it POSSIBLE that this system has no low-pressure service port, or am I just still not finding it? W hat says O ppo ?

DISCUSSION (21)

Brickman > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/05/2019 at 22:30

There’s gotta be one lol. Low side is the suction line, how else could the factory add refrigerant. Checked behind the compressor?

gmporschenut also a fan of hondas > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/05/2019 at 22:33

Dumb question is the condenser clean and not packed with dirt?

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > Brickman
07/05/2019 at 22:34

yup. looked there. no go. I don’t understand it either. WTF is it??? is it possible it’s right on the evaporator inside the blower box?

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > gmporschenut also a fan of hondas
07/05/2019 at 22:36

yes. that was my first step.

ITA97, now with more Jag @ opposite-lock.com > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/05/2019 at 22:36

Take a look at the low side pressure switch. Removing the switch may reveal the coupler for the low-side port (or the treaded shrader valve to attach an adapter onto ). I’ve seen an occasional A/C system where the port for the low side switch doubles as the charging port (which requires bypassing the removed switch with a jumper to charge).

My parents old 1st Gen Dakota used such an arrangement:

Unscrew t he pressure switch, attached a 134 coupler adapter, attach manifold gauge set, bypass low pressure switch with a jumper to charge.

My X-type is too a real Jaguar > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/05/2019 at 22:37

My Dodge has the low pressure port right on the evaporator tank, it took me a min to see it

Brickman > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/05/2019 at 22:37

Possibility . Try fitting a low side hose to the high side port you found. It could of been the low side port?

Then it could only have one port, as its not a highway vehicle and different regulations?

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > ITA97, now with more Jag @ opposite-lock.com
07/05/2019 at 22:39

T his is good info! I will check that! Thankyou! I did find the lowside pressure switch...

I like cars: Jim Spanfeller is one ugly motherfucker > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/05/2019 at 22:39

Delete AC, it’ll make it lighter more powerful and faster

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > Brickman
07/05/2019 at 22:41

It’s def a high-side port, its larger and the cap has an “H” on it. ITA97 may be onto it...

ITA97, now with more Jag @ opposite-lock.com > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/05/2019 at 22:43

It is possible the s chrader valve that switch mounts to doubles as the service port. Also take a look at drier itself. Sometimes the service port can be directly on the drier, G MT400 style.

Brickman > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/05/2019 at 22:47

Im done then :P

DC3 LS, Fuck Hyundai, now and forever > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/05/2019 at 22:49

I guess I’ll mini-hijack this thread to avoid making a new one.

What could cause an A/C system only work for a few minutes when turned on, but blow warmer, but still cooler than ambient air, a few minutes later?

The first time this happened, there was belt squeal when I turned it on.

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > I like cars: Jim Spanfeller is one ugly motherfucker
07/05/2019 at 22:52

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > My X-type is too a real Jaguar
07/05/2019 at 22:53

That would require disassembling the blower mani fold to locate... I am currently liking ITA97's idea....

I like cars: Jim Spanfeller is one ugly motherfucker > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/05/2019 at 23:08

TBH I did not know you could get a tractor with AC. Huh.

Rusty Vandura - www.tinyurl.com/keepoppo > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/06/2019 at 01:29

Upgrade your tractor.

Chinny Raccoon > I like cars: Jim Spanfeller is one ugly motherfucker
07/06/2019 at 02:28

I think it’s on virtually all new ones, wither the exceptions of the very small/budget models where it might be an option.

AMGtech - now with more recalls! > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/06/2019 at 09:35

I’ve seen systems without before. With an actual AC machine you can recover, evacuate, and recharge all from one one port.

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > ITA97, now with more Jag @ opposite-lock.com
07/06/2019 at 18:42

1: you were correct, the port is accessed by removing the pressure switch and connecting an adaptor.

2: Refrigerant charge was NOT my problem! I had high- low and low- high pressure when the g au ges were connected and the compressor running, but a static pressure indicative of a sufficient charge.

So I went looking for information about A/C systems in general, and with the help of pictures and you tube videos was able to determine that the system uses an H-block-style TXV regulator to create a “constant superheat ratio” in the evaporator as opposed an electronic, or pressure differential regulation system. The high-low and low-high pressure situation in one of these systems is indicative of either a stuck valve in the H-block, poor evaporator airflow, or poor thermal coupling (or thermal contamina tion) of the evap inlet and outlet. I disassembled the evaporator plenum and discovered that the insulating tape had fallen off the H-Block! This was causing the inlet and outlet temps of the evaporator to be “contaminated” by ambient temperature, leading the valve to “ think” the evaporator was unable to create a temperature differe n tial, so it was dumping excess flow through it in an attempt to do so, counterintuitively, (because A/C is black magic) excess flow through the evaporator leads to incomplete evaporation, reduced total flow volume (bec au se the refrigerant is moving as a liquid instead of half as liquid and half as gas) and a corresponding raise in l ow-side pressure and drop in high-side pressure, as well as crappy cooling performance. I re-wrapped the H-block and reassembled the plenum: T a da! B lows cold again!

without the recommendation that the switch could also be the low-side port I would never had diagnosed this.

ITA97, now with more Jag @ opposite-lock.com > JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t
07/06/2019 at 18:55

Nice find! Yet another example of why I also advocate against those “recharge” kits sold at retail stores with a low-side gauge attached to cheap plastic valve and can of R-134a. If you’re not looking at both sides of the system, you don’t really know what it happening with it.