The temp here been below freezing for a while, anytime I cold start my S40, power steering seem to be locked, for about a minute, then loosen up and works fine.
I made sure power steering reservoir has fluid although hard to see where min and max level markers are.
Also tried driving the S40 right after cold start, it drives fine but no steering before power steering unlock.
I wonder if this is how all S40's act after cold start or mine has power steering problem?
Would be nice to hear from others with similar power steering issues.

 

You should have steering assist from the moment the car starts. It has an electric pump so if the fluid is fine then I would look at the pump itself to see why it's not working when cold.

 

Temp now in 30's and it is not acting as such no more. The pump is smooth and quiet.
However it seem when car key is out the steering wheel is locked regardless of direction of the wheels, could the problem be with misbehaving steering wheel lock/unlock mechanism?

 

It all depends on what you mean by "locked".

If you mean that you can pull on the wheel with great force without it moving an inch, and then suddenly it's free and easy to turn... then yes, it could be the SCL (Steering Column Lock) mechanism freezing up. They're known for that though you usually get an error message when that happens.

If, OTOH, by "locked" you mean that the wheel is really, really hard to turn for a while but that the steering wheel DOES turn with more effort than normal, then you're just looking at a problem with the power steering pump / rack / circuit. The power steering fluid is thicker when it's really cold out, so if there is some sort of restriction in the system (or other problem) it could cause hard steering. I've had a number of cars over the decades that had stiff steering when they were really cold, but I can't remember ever troubleshooting one... if the steering was normal after 20-30 seconds I'd just chalk it up to the steering being "cold-natured".

 

Thank you,
with temp now above freezing (32 F) , it is hard to replicate the problem, it turns right away after the start.
I would flush the PS fluid in April just in case could help next Winter subzero temps.
When it was locked up I really did not try to force it to see if wheels turn hardly as there is no power steering or the lock is engaged, so that remains unknown.

 

you can do a fast flush now - find a turkey baster (not recommended to steal the one from the kitchen :-) - use it to suction out all the fluid from the reservoir, refill to full using fresh/correct fluid (usually its just ATF so easy enough to find. Start the car and turn lock to lock 2-3 times. Shut down then repeat removing all the fluid from the reservoir, refill, start car and go lock to lock. After about 3 or 4 drain fills, you should see the fluid look new. Total cost should be $10 ($3 for the baster and $7 for one quart of ATF) and you don't need to go under the car etc.

 

That is what I am going to do in April, FYI I just bought one liter Pentosin CHF202 for $18.20, my internet searches say this one is the best for Volvo S40.
I did a re fill on 3/11/19, the original fluid should have been Volvo(greenish to start) was almost dark grey to black, refilled it with most of Pentosin can( near one liter),
temp was 29 F degrees this morning and I had power steering as soon as engine started, it's unlikely temp falls below 15 F before next Winter, but I know next year if changing dirty fluid worked or not.