[vigsom]

A/C in my 2003 Corolla H4 has kept me busy for 10 long months ; http://www.team-bhp.com/forum/techni...hlight=corolla (Corolla A/C Problem - Diagnosis,Solutions,Experiences)

Having faced loss of air conditioning several times , decided to get the evaporator coil checked.

The old evaporator coil was observed to be leaking when tested at 150psig . Replacement coils were of two types,some unbranded stuff for 4k and OE for 6.5k ; settled for the latter

The job was done in my presence over two half days ;

• 1.5 hours to remove the dash (including removal of the evaporator coil)
• 45 minutes to re-assemble the HVAC container
• 3 hours to re-assemble the dash and ,
• 2.5 hours to commission the system

* Total time 8 hrs
* Total maal INR 9500 (OE evaporator coil plus service cost)

Key Learning

If you face a loss of refrigerant pressure in ,say 4 months,and do not see a pressure drop during the system pressure test,DO NOT hesitate to open up the dashboard and check the evaporator coil ; this coil was very badly fouled with tight muck and apparently the muck did not allow the leak to show up ; only when the coil was water washed and tested separately did the leak show up.

I'll summarise the steps and share a few pics .

I can write a long stepwise procedure but that'd be too much to digest.

Summary:

1. Allow the engine to cool down - say 30 minutes
2. Remove refrigerant
3. Disconnect Battery -ve to prevent DTCs later
4. Disconnect the coolant hoses to the heater core and the ac low pressure and hi pressure pipe joints at the engine bay firewall
5. Remove the dashboard in three parts - the console surrounding the gear lever comes out first , then the top half(the brown one),and finally the beige center portion(the part holding the glove box)
6. Remove the BCM and the ECM carefully
7. Remove the tubular frame on which the dashboard and the steering column are mounted
8. Remove the entire HVAC assembly ; this is the virgin white bodied plastic assembly which houses the blower assembly on the left and the heater+cooler on the right
9. Remove heater core ,then the expansion valve,then the ac damper motor,
10. Open the case to reach the evaporator coil
11. Put the evaporator coil back(new coil OR old coil after service)
12. Reverse the process of dis-assembly to assemble back

Precautions

1. Disconnect the battery -ve before starting work
2. Open the airbag connectors at least 2 minutes after the batt has been disconnected
3. Allow the engine to cool adequately before disconnecting coolant pipes to the heater core ; the hoses ,once disconnected must point upwards to prevent unnecessary loss of coolant.
4. Do not use a screwdriver to pry open the refrigerant pipe joints ; just open the clips and pull the joints apart
5. Use refrigerant oil on the o-rings before fitment ; prevents o-ring damage
6. Ensure that screws/bolts are kept where they are removed from - makes it easy to fit back
7. Ensure that the system pressure test is OK before re-assembling the dashboard
8. Do not reconnect the battery wire unless the Body Control Module,the ECM and the airbag connectors are fitted back.
9. Once disconnected,place the airbags upright ; the portion which opens up in case of impact must point upward

Points which we missed during re-assembly

1. forgot to connect the wiring socket of the interior lights since that harness was lost in the wild

Now for the Pics.

1. all hell let loose - wiring harnesses all over
2. the expansion valve
3. the heater core - after 8.5 years looks brand new
4. the old evaporator coil - found to be leaking when tested at 150psig
5. the new OE evaporator coil
6. the HVAC assembly back in place
7. the refrigerant pipes with the clip on couplers - super simple
8. the dash getting assembled ; note the Body Control Module at the top where you see a yellow socket - this controls the power windows and the interior lights
9. Almost done

[honeybee]

A detailed and nice write up. I only suggest you add some photos of the entire setup before the dashboard and the HVAC were taken apart, so the readers may benefit by knowing which things are where.

[vigsom]

one more issue was faced during the leak test ; the pressure switch at the condenser outlet was found leaking from the contact pins ; strange.

Lucky that it did not leak after the refrigerant was charged

[sgiitk]

An excellent account. I wish you had added this at the tail of the older one (reference in your first post). I am still keeping my fingers crossed, that now it is fixed (I am quite confident that it should be).

[vigsom]

Just to add for the benefit of Corolla owners

None of the old Corollas I have seen till date have a cabin air filter ; just the housing tray with no mesh

I have cut out a portion of galvanised iron mesh and am using it in the cabin air filter housing tray(this can be accessed by opening the glove box).

At least this arrangement will stop fine leaves/twigs from coming in(in case the fresh air mode is selected)

Plan to install something finer ; am looking for "jugaadoo" alternatives

[flipsyde]

@Vigsom - True the old Corollas don't come with a Cabin Filter. But you can get yourself a replacement from the A S S. Costs under 1k I think. A worthy investment I feel as my car's coil was choked with dirt and grime from outside. I think I saw some dried leaves as well.

[manishk123]

Thanks for that detailed guide. I found it while searching the net for the cost of the evaporator. The Toyota service centre quoted Rs.20,000 just for the part, plus gas charging, labour etc totally amounting to Rs.25,000/-.
Then found another AC workshop who agreed to do the same job with OEM parts for 11,000/-. Have gone with that. He is giving a guarantee of 1 year.

[Automaton]

Had the same problem on my 2006 H5 on Sunday.

The pictures were great, filled in all the action that I missed while it was being repaired and I was stuck in a studio.

Went to the local dealer on Monday. Got an appointment for Tuesday, kept the car till Wednesday evening and got a estimate for Rs. 28,000 to change coil, compressor case, charge gas, etc.

I found it hard to digest that, having done some homework in the forum.

Went the next day to the Premier AC at Prabhadevi (where I had got a Subros compressor and work done for my old Esteem a year and a half back, sold since.) where knowledgable Mr Bhasin gave a saner guesstimate for Rs.11,000.

They finished the work yesterday, in 5 hours, with a Denso cooling coil, 'O' ring, valve pin, filled in gas and compressor oil, and a retrofitted non-OEM cabin air filter, all for Rs 9,900 (incl. labour and tax).

Now got better air flow in the cabin. Today I drove around in the Mumbai heat at 24C and later in the afternoon at 25C, which was 22.5C and 23C before the new coil was fixed and the system cleaned.