Hi, Any Comments would be really appreciated. I Just installed the new Air Pump (and ck.-valve). (about 55°F here in Cleveland OH) I started the car cold and monitoring the air pump...it wont' run !not even in gear or under throttle. Maybe the relay is bad?. Help Any Ideas? What (sensor) tells it to run???
Where is this part? is there only 1 relay that runs it or is it in unison with a temp sensor & where is it? Sorry for all the ? but I'd like to say my job was done before closing the hood :).THANKS
D~
PS> I didn't really need to change the air inj valve as my old one was fine !

Hi I there is a nicely detailed how-to article with photos at VOLVOSPEED.COM...Look under the repairs section..The section is called BAY13..LOOK IN SUB-CATEGORY ..ENGINE..AIR PUMP...Perhaps you missed a step when you installed the pump..I decided to let the dealer do it and paid $650..for pump, sas valve and labor...just an idea...I hope it helps..........

Engine temp determines when the pump runs. I believe it must be below 55c. On the 70 series, it does not run till the ECU sees road speed. The best way to test is to have a scan tool conected and monitor the pump. It is controlled by the ECU via temp info from the sensor ot the t/stat housing. The relay is located in the main fuse box attached to the strut tower. Relay failure on 70 series is not common.

The ECU normally controls it and it's also not going to run when outdoor temps are too warm, don't know the temp specs. When it's cold out, the air pump only runs for short bursts to heat up the cat. convertor. Relay problems in newer cars like a '98 is rare and I wouldn't assume you now have a problem.

Why did you replace the pump, noisy or check engine light with codes?

The dealers scan tool can manually run the airpump at will so if you're really concerned, you could always have them run it to be sure it's functional. If it was me, I'd just drive the car as-is and see if you see the check engine light returns (assuming that there were codes and that they've been cleared with a scan tool.....NOT by just disconnecting the battery).

I'd like to add that the air pump doesn't only run just after startup either. I've noticed mine coming on after I come off a highway and idel for a few short time.

WOW, Lots of great help from everyone. Thanks ! ! ! I will check some more things out and I'll bet I don't have an issue. The fact that the airpump is controlled by the ECU via temp info from the sensor ref: t-stat housing and maybe other sensors, It may be a while for me as the wheather has warmed up here in Cleveland! worse case bad relay?fuse? or other probs=$DealerBuks$
I'll let everyone know what I come up with. Thanks again! This is a great bunch.
D~
BTW: I replaced the AirPump as it was filled with water so bad even the Electrical motor was filled solid. The rusty fluid(& I'm sure its acidic water as generated from the exhaust) I poured out would have killed anything. I put a new pump in and drilled my own series of very small holes in strategic places in the plastic volute case after I had totally dissassembled the old pump. You know- I could have fixed the old pump If I had a source for this Elec Motor' bout the size of a pop can... seems standard RPM with a 12 bar commutator. "Ya I worked in the motor industry for a while and this kind of stuff is do-able"
Also the Secondary Air valve was fine, I bought & put the new one in anyway!

I removed my pump this past winter because it was squealing and gave a CEL. This, mind you, is about two years after it and its check valve was replaced under warranty by Volvo because of the water issue. I found NO WATER in mine this time, only squealing bearings/bushings. I had to grind off the rivets to get inside the fan housing, but could get no further to actually get oil to the bushings. Since the battery was disconnected, this reset the CEL. The motor still squeals however. I'd really like to know how you got your motor/fan assembly further apart. Did you get the fan off and disassembled enough to be able to lube the bearings? How did you do it?