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3rd October 2024, 10:04 | #1 |
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| Rejuvenating my Maruti Suzuki A-Star's AC Background My plucky little 86K run 2009 A-Star is a senior now. It has seen 15 summers, passed the infamous RC renewal inspection without a fuss and is legally all set for the next 5. On the onward leg of a 1700Km Bangalore-Honnavar-Goa trip in June, the cooling started feeling inadequate. It was not a drastic drop, but rather a gradual loss in performance over the months which we were able to bear until the blazing afternoon heat exposed this weakness. After fighting off horrific thoughts of a demonic mech gouging out bits of my spotless dashboard to reach an imaginary leaking evap core, I pulled over and checked the following: - Coolant levels and general feel of engine heat - all ok - Radiator fan functioning normally - Removed the cabin air filter to facilitate smooth air flow - Checked condenser for damage - none observed The AC was functional with cool air at the vents, but it had lost its muscle. Mind you, cooling was never a strong point of the A-Star even from the factory. With a mental note to look into it in a relaxed and systematic manner, we completed the 9 day trip without much discomfort thanks to the bountiful rainfall along the coast. Some pics from the trip for viewing pleasure. By the many rain-fed micro-falls Through the whisper-quiet forests Over the expansive plateau By the stormy sea Through the foggy ghats Last edited by rajathv8 : 4th October 2024 at 16:41. |
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3rd October 2024, 15:28 | #2 |
BHPian Join Date: Apr 2008 Location: Bangalore
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| Re: Rejuvenating my A-Star's AC Though I get all the services done at MASS, I have always declined a wash to save the bodywork from inevitable sandpapering. Hence, my first suspect was a dirty condenser at least partially contributing to the issue. The evap core should ideally be in better shape since I have been using a cabin air filter. This was confirmed by bhpian vigsom at one of our meets along with diagnosis of low refrigerant levels with an audible hissing noise in the cabin. Stage 1 : Condenser cleaning My initial thought was to spray on some car shampoo and wash with a strong stream of water, but after some research I decided to take the foaming-cleaner route. Here is one of the many very satisfying videos showing the cleaner in action: I procured a 1L can of "Zed Shine" cleaner from the local AC spares retailer for Rs.150. This is a generic product meant for domestic ACs. I initially diluted it in 1:4 ratio and later dropped it to 1:2 for the final iteration. One would normally need to remove the bumper for effective application, fortunately the A-Star has a grille design with wide openings which did not necessitate bumper removal. Thank god for that since I had just got the bumper repainted and aligned prior to the RC renewal and I did not want to mess with it so soon! The foaming-agent alongside the yellow-headed sprayer I deployed for this task. Using the sprayer was a pain since it needed a billion pumps to effectively cover the condenser area leaving my hands looking like good old captain-hook at the end. The blue-header pump sprayer will be more effective and efficient. Mine unfortunately was dripping fluid from the nozzle and since I wanted to keep the reasonably-new-bumper-paint and corrosive chemical interaction to a minimum, I decided to stick to the yellow one. Foaming action along with dirt being pushed out. This was accompanied with unpleasant and strong odor so best to not attempt cleaning in closed confines/basements. After each iteration I hosed down the condenser with strong water stream. A hose is recommended over bucket/mug since the water passes through the condenser and does not spread around, thus requiring a million mug refills to cover the condenser area. The final hose down included the hoses and plastics on the inner side of the forward engine bay section. Using rubberized gloves is a must. As seen in the first video - this stuff is corrosive! After each iteration I removed my "flimsy" gloves and rinsed off my hands in water. At the end I had mild irritation felt on my hands despite using gloves. A closer look: I performed 5 iterations and consumed 500ml concentrate in total with reducing levels of blackish dirt in the runoff water stream. In the last 2 iterations I switched from a spray to a jet setting on the sprayer with the hope of reaching a bit of the radiator behind the inch-thick condenser. The runoff water had about 30-40ish bits of broken condenser fins. These seem to have dislodged from the edges due to age and do not appear to be a consequence of the cleaning itself. In the classic DIY spirit, I forgot to take pics of the "before" Here is the best I could pull out from my archives. It shows the blackish muck on the condenser and is a good representative "before" pic. This pic also shows the large gaps in the grille which allows for easy cleaning without bumper removal. Cleaned condenser with a sheen. Notice the fins breaking off at the edge. Just for reference, this is the fan side of the radiator taken prior to cleaning. Note how beautifully symmetric and nonmutilated the fins appear. Result: 1. Perceptible improvement in cooling but not nearly as much as it should normally be 2. Compressor was cutting out, which it did not do before, but not nearly as frequent as it should 3. Small drop in radiator fan noise, possibly due to lower restrictions in air flow and hence lower load on the fan All 3 improvements persisted through the fortnight between stage 1 and stage 3. After thoughts: These are the things I would like to do differently in the next attempt: 1. Use better gloves 2. Use a functional pump-sprayer. Will lower application effort/time significantly and also lower exposure time to potentially toxic fumes 3. Substitute the local-cleaner with TetraClean alkaline variant diluted 1:4 ratio Here is a video I found showing the results from acidic/neutral/alkaline versions of TetraClean. The foaming seen from the diluted TetraClean alkaline is easily 3-4x more than the local "Zed Shine" cleaner I used. The slogan on the Zed Shine "We deliver the best than the rest" did not prove to be true Last edited by rajathv8 : 4th October 2024 at 17:02. |
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3rd October 2024, 15:43 | #3 |
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| Re: Rejuvenating my A-Star's AC Stage 3 : Fin straightening As per my guestimates, ~5-10% of the condenser face has bent fins. Some are in singles but some have about 10-15 bent in a group. Each one of these restricts air flow all the way through the condenser and radiator. My intent was to bend some of these back using a wooden broomstick/toothpick. A worthwhile once in a car's lifetime TLC. However this proved harder that I imagined. The fins have been compacted into each other and the force required to bend them true vs bend them completely in the opposite direction seemed to be nearly the same! In few cases I ended up making things worse or breaking the fins off completely. In other cases it was super un-ergonomic to bend low and long enough to reach the little buggers. Some areas like the bottom right had the fins compacted so firmly that I could not pry them open with reasonable force. So, rather than ruin the condenser, I decided to let things be. In the image below, tiny grains/pebbles jammed in between the fins can be spotted. These are all over the condenser surface and were lodged in too tight for the cleaning process to clear off. I left these too. I may tackle both these issues if I happen to remove the bumper down the line. Last edited by rajathv8 : 4th October 2024 at 13:20. |
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3rd October 2024, 19:30 | #4 |
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| Re: Rejuvenating my A-Star's AC Stage 3 : AC Gas Recharge Next step was to subject the car to its first AC refrigerant recharge. For some unexplainable reason, I have very low trust in car AC technicians. So when vigsom offered to coach me through a DIY, it was a no-brainer. I picked up a 450g can of SRF Floron HFC-134a for a princely sum of Rs.300 and a brass can top valve for Rs.250. The valve has a coating which makes it look non-brass but is sturdier and heavier than the cheaper brass-colour valves. Note the Chinese branding on the valve. These too are available at local AC repair retailers. After picking up vigsom and his stach of colorful equipment, we scouted for a suitable location where we could work at peace. Few rounds of recce found us a lovely tree lined road by a lake. Conditions were ideal: hot-day to test the AC, tree shade to work in comfort, desolate place for peace and a lake that was not on fire! We got to work: 1. Status quo The AC was blowing only mildly cool air, irrespective of blower speed. The radiator fan and compressor was running and almost never cutting out even at blower speed 1. The low pressure (LP) line was just mildly cool to touch with only traces of condensation. 2. Engine OFF 3. Establish car side connections - blue line Screw the blue line to the gauge and to the coupler. Each end of the line has a nut with a washer for a snug fit. Close gauge valve Unscrew the LP line nipple cap Attach the coupler to the LP line nipple. This coupler is a spring loaded pull to attach/release type much like the one on the domestic LPG gas cylinders The couple can only be attached when the coupler valve is in closed position. With the connections done, the setup is passive and non-interacting with the car until the LP valve is opened LP valve coupling. The LP line has been insulated with black domestic AC insulation as part of a previous DIY. Notice the white unscrewed protective cover in the windshield cowl. 4. Check the LP pressure Open the LP line valve The gauge will now show the standing pressure in the LP line - it read about 80 psi with a hot engine bay Engine ON, AC ON, blower speed 4, doors open : basically loading up the AC From this point, engine and AC will remain ON till the end Opening the LP valve Checking the standing pressure with engine OFF - climbed and settled at 80psi. Please ignore all the rat protection mesh work in the engine bay 5. Purge the blue line With engine and AC ON, the pressure dropped to 30psi To purge the blue line i.e get rid of the air in it, slightly open the valve at the gauge for 2-3 seconds and close it. The pressure in the LP line will force the air out from the gauge end with an audible hiss. It is worth noting that the lines have thick walls to handle high pressures, and hence its inner diameter and volume of air in it will be very less. 6. Prepare the can The can top valve, with the valve in the most open position, should be screwed securely onto the can. The valve has a washer in it which will fit snugly for an air tight seal on the can stem The valve lock nut must be tightened to the can top In this setting, the can is still sealed. It will be pierced open a bit later when the valve is closed for the first time 7. Establish can side connections - yellow line The yellow line is connected between the gauge and the can The ends are not interchangeable, the gauge end has a pin within the yellow line, while the can end does not Can side connection with valve in open position. The can is cool to touch (just like holding any other metallic object) and feels weighty. 8. Purge the yellow line Loosen the yellow line nut at the can end Slightly open the gauge valve to allow the 30psi pressure in the blue line to force the air out of the yellow line with an audible hiss After a second of hiss, the can end yellow line nut should be securely tightened to the can Close the gauge valve Opening the gauge valve with can side nut loose for purging yellow line. Note the open can top valve (long valve stem length visible) 9. Pierce the can Now the can is pierced by closing the can top valve fully. Though the can has been pierced, only trace amount of refrigerant would have entered the yellow line since the can valve is in closed position Open the can valve Closing can valve for first time to pierce the can 10. All set to start charging! In this setting, the refrigerant vapor in the can is available at one end of the gauge and the other end is connected to the LP line. Since the gauge valve is closed, the two sides are isolated. The gauge valve is the single point of control required henceforth to allows/blocks the flow of refrigerant from can to car. Ready to start charging with the gauge reading 30psi 11. Refrigerant charging Open the gauge valve Refrigerant vapor flows from can to car since pressure in can is higher A spike in pressure is observed on the gauge, went up from 30psi to 45-50ish and dropped back to 30psi The can immediately feels colder to touch as the refrigerant liquid flashes to vapor in the can to replace the vapor that has flowed to the yellow line Close the gauge valve after 10 seconds or so Wait for 2 mins to allow the car AC loop to stabilize Opening gauge valve to charge refrigerant. Lake visible in the top left. 12. Rinse and repeat Repeat step 10 The standing pressure in the line creeps up about 0.5psi per iteration, we saw it increase till 42psi. But as the refrigerant charge in the loop increases, the compressor suction temperature drops and this lowers the pressure. So we saw a 30 at start -> 40 -> 42 -> 40 -> 30 at end. With each iteration, the LP line feels colder to touch and the line condensation sweating increases. After the pressure reached around 42, the blower speed was dropped to 2 and the doors were closed - this is to simulate normal usage condition and observe compressor cutout pattern. Standing pressure reading slowly climbing. Now showing 36psi. 13. Time to call it done? As the iterations continue the compressor ON time reduces since the larger refrigerant quantities allow faster evap core cooling. When the throttle is increased the ON time drops while the OFF time remains the same. The higher compressor RPM cools the evap core faster, hence the evap core temperature sensor cuts off the compressor quickly, however since the rate of warming of the evap core remains unchanged, the OFF time remains the same. Compressor settled to a 20-7 seconds ON-OFF cadence at idle. When the vent and cabin temperature felt adequately cool for an engine idling condition, the condensate sweating on the LP line had reached larger drops and the line itself felt frigid to touch, we decided to call it done. At this time the can was significantly colder to touch. It had developed condensation. 14. Disconnection and winding up Gauge valve is in closed state from the last part of step 10 Close the can top valve tight - not to be touched till the next refrigerant recharge Now the can has been cut off from the charging system Open the gauge valve Allow compressor to cycle few times. The high pressure refrigerant remaining in the yellow line will be sucked into the car LP lines Close the LP line valve Now the car has been cut off from the charging system Unscrew the yellow line from the can end. Small hiss will be heard as the 30psi in the line equalizes to atmospheric pressure. However, the hiss should not be prolonged as it could indicate an incorrectly/partially closed can valve. De-couple the blue line coupler from the car LP line nipple - no hiss Screw the protective cap on the LP line nipple Can closed firmly until the next time (short valve stem length visible). 15. Engine OFF Results: - Bone chilling AC like it was never before - Compressor cutting out more often along expected lines Few additional points: - This exercise was all about knowing which valve to open/close, when and in what order - Can and Gauge valve are screw in to close - LP valve is screw out to close - Usage of gloves is recommended Acknowledgement Special thanks to vigsom for his time, guidance, equipment and for clicking all the recharging pics too! And that's a wrap! Thanks for reading Last edited by rajathv8 : 4th October 2024 at 17:06. |
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4th October 2024, 17:35 | #5 |
Team-BHP Support | Re: Rejuvenating my Maruti Suzuki A-Star's AC Thread moved out from the Assembly Line. Thanks for sharing! |
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5th October 2024, 10:45 | #6 |
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| Re: Rejuvenating my Maruti Suzuki A-Star's AC While this a a great DIY, it would be better to find a car AC technician that has a automatic gas charging machine and get it done there. This DIY skips THE most important part in recharging refrigerant, vaccuming the system. Without that traces of air and moisture would be trapped in the system, leading to damage to the system in the long run. The automatic gas charging machine does all the work automatically, so there is no risk of air entering the system. |
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5th October 2024, 16:39 | #7 |
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| Re: Rejuvenating my Maruti Suzuki A-Star's AC Nice DIY. Honestly though, I wasn't able to digest a single line you've mentioned, because all I was able to see was the photos of the gas canister and gas canister and more gas canister. DIYs elicit a sense of happiness like no other, keep it up. Cheers! VJ |
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6th October 2024, 07:25 | #8 |
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| Re: Rejuvenating my Maruti Suzuki A-Star's AC You missed the most important step of pulling vacuum from the system before filling refrigerant. Also you needed to add some oil into the system for the lubrication of the compressor, else it will run dry and fail prematurely. Good effort on the diy though. |
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6th October 2024, 12:14 | #9 | ||||
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| Re: Rejuvenating my Maruti Suzuki A-Star's AC Quote:
I personally opted to aim for my feet via the DIY route for the curiosity, learning and camaraderie it fosters. I certainly would not recommend everyone to try this. For this DIY as mentioned, the blue + yellow line was purged thoroughly. I am confident that no air/moisture has entered during the DIY itself. About the air/moisture already present, since the closed loop is under pressure > atmospheric pressure, I presume any leak should be outward i.e from car to atmosphere and not the other way around. Is there any way for air to enter the higher pressure system? (This is the first refrigerant recharge post factory) Quote:
Quote:
The cooling seems to be holding up at least for the last 3 days so it appears there is no major leak. Slow leak in a 15 year old car is something I can live with. Quote:
Thankfully vigsom captured some images which I could leverage. Last edited by rajathv8 : 6th October 2024 at 12:18. | ||||
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