Spray it from the back - the bugs 'n stuff come in from the front so you want to push them back out, not bury them further. Car wash pressure can be risky if you get the nozzle too close - better to use a garden hose as others have said. If that's the original rad it's getting old and delicate. Draining coolant can be messy unless you take off the bellypan, but once done, pulling the rad completely out is a cinch. Then you can give it a very thorough cleaning, plus reverse-circulate the core (shoot water in the bottom spigot) to help dislodge crud. You also get a clean shot at the back of the AC condenser.

On our 83, despite regular coolant changes and flushes with Prestone's chemicals, the rad was 50% plugged with internal deposits in the tubes. They rodded it out and the flow improvement was impressive. If external cleaning doesn't show an improvement in cooling ability, pull it and take to a shop for evaluation.
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Bob (81-244GL B21F, 83-244DL B23F, 94-944 B230FD)

Hi Susan, you can do this at the carwash, or at home as people recommend. I'd do it at home. You can start by opening the hood and taking the grille off. To get to cleaning both the a/c condensor rad. and main radiator it may be a good idea to unbolt the two radiator clamps that hold the radiator in place (clamps from the rad. mounted to to the frame) You can also undo the transmission cooling lines. Remove the fan, fan shroud. Now you can partially lift the radiator out of place. Use a thin tool (such as a putty knife) to straighten the bent fins on both radiators. You can then use a brush to sweep away and debris that is stuck in the cooling fins. Spray it down with a degreaser. Maybe a mixture of dishsoap and water may work fine in a spray bottle. Let it sit for awhile, then spray off with a high pressure hose (you can find a high-pressure hose tip at a hardware or garden place, and I think about $1 to $2). After all is clean sit radiator back in place properly, screw everything back up and your on you way. I did this about a month ago and the car runs a bit cooler believe it or not.
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Michael 'Street'... one AZ '85 244DL 189K miles

It's probably better doing it with a garden hose, as suggested by Riglee, from the engine side. The car wash pressure might destroy your rad.

You've got an old rad, the "corrugations" in the rad may crumble at high applied water pressure.

Try pressing the rad face areas with your finger and see if it is solid. If not, it might be time for a new rad, assuming there are indications of overheating.
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1980 245 Canadian B21A with SU carb and M46 trans

You might also take this opportunity to straighten any bent or crushed fins that you see. This often happens during less-than-careful installation of the radiator or engine work. Bent fins will reduce the cooling abilities of the radiator as well.

You can slide a screwdriver in between the fins to pull them straight or you can get an inexpensive plastic tool from a store like Pep Boys. As long as you're reasonably careful, you won't risk damaging anything.

The above applies to the AC condensor too.
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'84 '285' rice-eater with lotsa hp & performance goodies

The best tip I can give against hot running, without mods =

change your coolant to 70% water/ 30 % glycol.
Now my temp meter is 8 hours 50 in stead of 9 o clock in hot summer temps.


The thermal capacities of pure (100%) are superior to any mixture of glycol / water.
Glycol is added as antifreeze and temperature riser of the cooling system.
The glycol reduces the thermal capacities of pure water.
BUt VOLVO rads are designed for this mixture (as all cars).

I drive a 30 % glycol and 70 % water: this keeps the engine always EASILY at temperature (moderete climate).
This certainly helps cars with AC, because a 30/70 mixture can draw off more heat than a 50/50 mixture.
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When I did my head gasket, I removed also the rad and flushed inside countercurrent.
A lot of small deposits were coming out.
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240 '88 B200K wite sedan 255K km Europe virgo+all turbo gauges, Phoenix Gold + Kenwood ampli, Focal door speakers + tweeters, Kenwood 6'x 9', 10 CD changer in enlarged globe cabinet, dubble rear coil springs , hitch, fog lights, 2 extra rectangular pencil

The pressure at the car wash may bend the fins. No need to do it there: do it with a hose at home. Remove the fan shroud, spray some detergent on it, and spray from the engine side. You can loosen the a/c condenser in front by removing the clips on top and make sure that is clean too.