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Late shifting

Question : I HAVE a 1996 Proton Saga, 12-valve auto.

Last February, I did an overhaul and the engine is running fine, except that I'm facing serious problems :

1. The auto gear box : Each time I start the engine any time of the day, the auto transmission does not engage until the engine has warmed up. Also, when it starts to move, it will revved up to 3,000-4,000rpm before engaging to the next gear level. After that it will engage smoothly. I don't face any problem with D2 or L. What is the problem?

Things that I've done - I have changed the oil seal and top up with ATF when I did the overhaul. My mechanic advised me to drain the present ATF, and change to a better quality. What do you think?

2. Air-cond : It blows only hot air during traffic jams or in the afternoon. It is only cold in the early morning and night time.

Things that I've done - I have done the usual service such as clean the filter and blower as well as fill in the gas. What parts do I need to service or change?

Answer :

1. I do not think your problem is with the ATF. I think you have a problem in the valve block or sometimes called the 'brain' of the transmission. When you shift into D, the hydraulic fluid is routed to several shuttle valves which route the fluid to cause the changes.

I suspect that the 1st and 2nd shuttle valve is sticking and that may be the reason for the late shifting. However, when you manually shift into any particular gear it seems to run OK.

Get a competent auto transmission mechanic to have a look at the valve block. He may have to pull it out and service it.

2. The obvious thing to look at when the air-conditioning is not cold is to charge up the gas or refrigerant.

However, the problem could be with the compressor itself as it may not be able to compress the refrigerant sufficiently due to wear, or the thermostat may be faulty.

Get someone who has the right tools to check out the pressures in the system and the operation of the thermostat. You will be able to see that it is not that big a problem after all!


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