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Restored AC cooling on my 15 year old A-Star: Here's how

29th November 2024, 14:28 by Ananth Iyer

This exercise was all about knowing which valve to open/close, when and in what order.

BHPian rajathv8 recently shared this with other enthusiasts:

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

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:

http://www.youtube.com/watch?v=wx5rn32kT18

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

http://www.youtube.com/watch?v=R1xmts7zkrw

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.