Starting to put my 740 to the test and I'm pleased

After spending the last 7 months getting my 1987 740 in shape, I am
finally starting to see dividends. The point was to spend the money
necessary to get this car capable of being my everyday commuter. I sold
my Honda to eliminate a car note ($400) because I only live about 8
blocks from work in a small town.

For the first time in those 6 months, I've been able to test the Volvo.
In the last 2 weeks I've made 2, medium distance trips with my wife and
son. The first was a 200 mile round trip to the airport, at night. It
was quite interesting for me to be that far away from home in a 20 year
old car with 200,000 miles on the tranny and me having done much of the
work. The slightest glitch could have stranded us -- but the car did
well.

The more recent trip was a 250 mile recent trip, this time in 105 F
heat, stop and go traffic, hat as can be! The car did great, but I
sure am working that air conditioner! I don't have an aux fan hooked
up, so if I am doing 70 mph + on the highway, it blows very cool (54-58
on low/medium and 60F on high). But, stop and go traffic in 105-110F
temps and the best she'll blow is 70-76F.

I want to make sure it has no leaks, but if the temp is 95F or less, it
blows always at 54-56F. If the temp is in the 80's, it blows 40F. It
is definitely relative to the outside air and this is a bug or
something I want to fix.

Anyway, this car is one tough cookie!!!!!

JB

 

That's normal, an AC system maintains a temperature differential between
the inside and outside. Your 740 has a simple system with a fixed
orifice expansion device so the ideal amount of refrigerant will be
sprayed into the evaporator at one particular indoor and outdoor
temperature, any other condition is a compromise. Better systems use a
thermostatic expansion valve (TXV) which meter refrigerant based on the
temperature of the suction line, those will hold a much more constant
temperature but you don't see them as much due to the higher cost.