[vigsom]

Introduction

In my close to 40 years in automotive, my favourite area has been technical stuff, and under the technical umbrella, my most favourite subset has been air-conditioning. To substantiate this claim, here is some stuff that I'd created

1. Car Aircons - Part I (Aircons! Demystifying the car air-conditioning system)

2. Car Aircons - Part II (Aircons! Demystifying the car air-conditioning system, Part 2)

3. Car Aircons - Part III (Mitsubishi Pajero Sport | Diagnosing an Ultra-Low Leak in the Aircon System)

By the time Part III was published, I'd almost had enough of the shoddy practices of many car AC technicians. Most of us cannot do without ACs (aircons) today; it's become that addictive and therefore, service providers hold us to ransom.

Why this thread?

This subject has been discussed via this marvellous thread by friendly mod @Gannu_1. I'd not repeat what has been already been beautifully described by @Gannu_1, but add some details on my initial steps towards atma nirbhar (self reliant) air-conditioning in DIY mode.

[vigsom]

The driver towards atma nirbharta (self reliance)

I was out of action for a while due to a bypass graft surgery, and one of the cars seemed to have gone a little low on refrigerant apparently over time and due to little to no usage. I wasn't sure whom to go to for aircon in a new city. I was wary of landing with the wrong people. However, having operated large hydrocarbon refrigeration systems, and being fully aware of the risks, undertaking refrigerant top up was small fry. I decided to roll up my sleeves and do it myself.

Why would the car aircon go low on refrigerant?

I'd got the car's aircon all done up in mid-2021. Even with a healthy condenser, healthy evaporator core, healthy hoses/ piping, the only weak points are the joints (o-rings) and the compressor seal. Standing pressure in the system would go as high as 130psig in a warm engine bay. A car's aircon (AC) holds anywhere between 450g and 900g and very very small amounts of refrigerant escaping from seals, joints isn't uncommon, especially on older equipment.

Actions taken to move towards self reliance

1. Scanning the on-line marketplace: My first step was to scan the Indian market to see what was available and at what price point. I looked at amazon and flipkart casually just to gauge price points. However, being fully aware of the risks of getting substandard and unsafe stuff, I was no way taking the on-line marketplace route.

2. Scanning youtube : I did this just to get to understand price points of various products over a wide spectrum of perceived quality

3. Scanning the local marketplace : I then looked at aircon spares dealers/ distributors, did my dissection on their published ratings, and went shopping.

Findings during shopping

Aircon spares retailers are aplenty but I'm always wary of them for fear of being shooed away for the questions that I ask. However, I found a distributor, whose rating was reasonable, but finding the place in an old building was like traversing a crystal maze. After a few misses, I eventually landed there. The owner was kind enough to help me with various available options

1. Refrigerant (R134a) : SRF Floron, Mafron, Value, Blue Star and Chemours
2. Double manifold gauge (low side blue, high side red plus 3 charging hoses blue, yellow and red : Options - Grade1, Arham
3. Compound gauges low side blue (full vacuum to 250psi): with sight glass with hanging hook vs without sight glass - Grade1, Arham, VALUE
4. Gauges hi side red (0 to 500 psi) : same options as item #3
5. Charging hoses : a) length options 90cm, 150cm, 180cm b) Brand options Arham, Husky (Indian), VALUE
6. Car low side and hi side couplers : local grade1, local grade2, VALUE
7. Refrigerant can valve : only one option available

I wanted the very best in everything because this could turn out to be a good long term investment, but the stuff was overshooting my estimates by a mile. However, almost when I was closing in on getting these, the folks at the place disappeared to their Godown to execute a big order and never returned for almost 1hr 45mins. I'd already lined up a couple of other things to do and this wait irritated me, so I left the place. Met the owner on my way out and told him I had two other jobs to finish and so I'd get back later.

Meanwhile, I completed the other two tasks, returned home, did some more due diligence on what I actually needed, asked around at a couple of retailers. Although the prices weren't too much off, what made me get back to the distributor was the authenticity of the products, a GST invoice, and availability of a wide range of refrigerants

Finalising the purchase

I went back to the distributor in the evening, and examined all options again. My choices and the logic therein are as follows:

1. Refrigerant : Chose Chemours as this is considered better than the rest. Also my cars have been running on Chemours
FYI - Chemours is just 35 bucks more expensive than SRF Floron. Based on brand, R134a retails for between INR 350 and 500 a can of 450g
2. Double manifold gauge with hoses : INR2100 - rejected as I am a little wary of a manifold that has both high side and low side valves on the same rail. If the high side valve passes, it can cause havoc
3. Compound gauge low side blue : Arham vs VALUE. I chose Arham on trial. Arham was close to INR860 while VALUE was INR1750
4. Pressure gauge hi side red : Did not procure as from experience, I am quite okay with just the low side pressure reading for a top up job. Decided to get the high side later
5. Charging hoses : Examined all the options carefully and it was a difficult choice to make. Finally went with the 150 cm hoses from VALUE. The difference in quality was evident and I strongly recommend 150 cm hoses over 90 cm ones any day. It helps, especially when the low and hi side ports are awkwardly placed, and if the engine bay is huge. Husky hoses were good but the finish quality of the crimping and the end threaded joints left some room for improvement. Arham was also good enough. Set of three hoses - Arham 90 cm was INR800, Husky 150 cm was 1400, VALUE 150 cm was 1700
6. Car low side and hi side couplers : chose VALUE for INR 1950 against the grade 1 which was a mere 1000 bucks
7. Refrigerant can valve - INR 295

Items 5,6 are in my view very critical to safety and for quick isolation and hence the choices.

Items not purchased

Hi side gauge - not purchased now


Compound gauge - VALUE - not purchased



Items purchased

Car low and hi side couplers from VALUE - later realised these have a safety interlock by design viz. the quick couplers won't disengage until the knobs are turned anticlockwise to disengage from the car AC port


Refrigerant - Chemours


Refrigerant can valve


Hoses 150cm from VALUE and Compound gauge Arham with sight glass and hook

[vigsom]

Understanding the components

The can valve must be kept open when fixing on the can. The valve must be closed only after one has connected the valve to the can, and to the hose and is ready to charge refrigerant

Refrigerant can - valve open (note the long stem length)


Piercing nozzle position when valve is open


Refrigerant can - valve closed (note the shorter stem length now)


Piercing nozzle position when valve is closed


How the valve is fixed onto the can - threads inside to fix the valve to the can and then a locking nut on the outside to lock the valve in position


one hose connected to the gauge on one side and car coupler on the other side - car coupler hooked to the low side port


Standing pressure in a warm engine bay - With the blue valve under the gauge closed, the pressure inside the hose will be sensed by the gauge. When the car coupler knob is rotated clockwise, the schrader valve pin is pressed allowing the low side standing pressure to be seen on the gauge


Switch on the AC compressor and the gauge reading would drop to indicate the system low side pressure - this pressure can be a little lower or higher based on ambient temperature

[vigsom]

Time for action

Having verified the hose, gauge, car coupler for integrity and their functioning, it was time for the top up. Unlike many technicians who charge with the can upside down, I went ahead with charging with the can upright to allow only vapour to enter the system. This is time consuming and the can would go rather cold. I followed the following steps (recommended to do in a shaded area with adequate ventilation):

1. Connect car coupler to the car's low side port. In the Pajero Sport, it was in a rather awkward location below the car battery. One needs to be careful else the hot surface of the compressor discharge line could cause a minor burn
2. Connect the other nozzle at the other end of the gauge valve to the yellow hose (as shown) to the can valve. Here the can valve should be in the open position (long stem) and just be screwed one or two turns on the can
3. Keep the blue valve below the pressure gauge closed
4. Turn the car coupler knob clockwise to allow the pressure gauge to read the low side pressure/ standing pressure
5. Open the pressure gauge valve 1/4th of a turn to purge off all air in the hose till the can valve
6. Once there is a hissing noise heard at the can valve top, tighten the can valve fully and tighten the lock nut
7. Close the blue valve at the pressure gauge
8. Close the can valve fully to pierce the can
9. Open the can valve to release refrigerant till the closed end of the pressure gauge valve. Ensure there are no leaks on the hose/connections till the pressure gauge valve end
10. Start the engine, switch on the AC. Settings : Blower air direction to face, speed full, temperature setting full cold, air set to recirculation mode, all windows open(as per recommended procedure). If there is a rear AC, set that to full blower speed position as well. The pressure gauge reading will now drop to somewhere around 30-40psi
11. Current status : Can valve open, Pressure gauge valve closed, Pressure gauge reading the system low side pressure
12. Open the Pressure gauge valve half a turn to release some refrigerant into the system. This will be accompanied by a slight rise in the pressure gauge reading
13. Close pressure gauge valve and allow system to stabilize for a minute
14. Keep adding refrigerant in small shots by repeating steps 12 and 13 until the air temperature at the vents is approx 7-10 degrees C
15. Once the top up is complete, close the can valve fully and open the pressure gauge valve to allow the refrigerant blocked in the yellow hose to flow to the system
16. Disconnect the yellow hose from the pressure gauge valve to open the pressure gauge valve port
17. Disconnect the yellow hose from the can valve; cap the open end of the can valve to prevent inadvertent release of refrigerant from the can
18. Close the knob at the coupler by turning the knob counterclockwise fully
19. Open the valve at the pressure gauge to relieve the blocked pressure in the blue hose
20. Disconnect the car coupler from the low side port
21. Fix back the low side port cover

What I did additionally

1. After I'd finished adding approx. 250g of refrigerant (during addition, the cold surface of the can gave me an idea of where the liquid-vapour interface was), I shut the pressure gauge valve off, closed all windows, lowered blower speed to approx. 40%(that I normally use), and allowed the compressor to cycle on and off
2. I felt "satiated" when I found the compressor cycling on for 10 secs and off for 10 secs on an average

Low side coupler hooked up - only thin arms can get in there


Kit all hooked up - the 150 cm long hoses helped; 90 cm hoses might have been a li'l tight


Refrigerant purge out via red arrows - low side port to blue hose to blue valve to yellow hose to loose can valve


At work


Key learnings

1. No task is difficult if executed with planning and with confidence
2. My joy of executing something even as simple as this knew no bounds!

[GTO]

Thread moved from the Assembly Line to the Tech section. Thanks for sharing!

Going to our homepage today

[Jeroen]

Thanks for sharing. Excellent job. Great to see this. I have never got around to getting the tools for my own DIY filling. Mind you, these days I have a friendly neighbour who used to run a car AC shop, so no need.

As you found out, good equipment is not cheap.
When we lived in the USA, the car part stores sold little complete AC top up kits. A small canister complete with hose, valve and manometer.

I have never seen those anywhere else.

No matter what, over time all AC systems do loose their charge, so topping up is always required at some point in time. But it can last. I topped up the AC in my Alfa Spider for the very first time well after 25 years!

Jeroen

[discoverwild]

Originally Posted by vigsom

Key learnings

1. No task is difficult if executed with planning and with confidence
2. My joy of executing something even as simple as this knew no bounds!

Getting to learn new things from you. It took me back to the 90s when I used to dismantle my Kinetic Luna Super moped and later my Hero Honda and service them myself. Your meticulous work on your Pajero Sport's overheating issue was what made me consider it as an option even as many dissuaded me. Though I loved the Pajero SFX, it turned out to be very uncomfortable. Speaking to you, gave me the confidence to choose the Sport.

Your help in narrowing down my vehicle from scores of vehicles on sale online, teaching me how to recognise differences in body panels and interiors, going through at least 30 examples from across the country, narrowing it down to 2-3 and the finalization of one, test driving the car with me - miracles do happen.

Have completed 4000 kms on it over the last two and a half months, and it leaves me with a wide grin each time. Parking it in my really narrow and cumbersome lot is actually turning out to be easy, with its amazing turning radius.

Your hospitalization, right after we picked up my car, was worrisome, to say the least. But your spirit and enthusiasm is such a rub-on. I'm glad you're back to doing what you do best. Contributing your wealth of knowledge to us lesser mortals. Wishing you good health always. Cheers, Som!